[GH-ISSUE #1182] LG HDR 4K monitor Contrast-control slider stopped working (no change in hardware or MonitorControl.app)

gitea-mirror commented

2026-05-05 06:30:37 -06:00

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Originally created by @johnnyutahh on GitHub (Sep 20, 2022).
Original GitHub issue: https://github.com/MonitorControl/MonitorControl/issues/1182

Before opening the issue, have you...?

Searched for existing issues
Read through the Monitor-Troubleshooting Wiki
Updated MonitorControl to the latest version (if applicable)

Describe the issue

LG HDR 4K monitor (LG 32UL500, full specs: https://i.imgur.com/uPQ2wFC.png; advanced settings: https://i.imgur.com/sj4ZV8X.png) Contrast-control slider stopped working after no other, apparent change in hardware or MonitorControl.app v4.1.0 app. Downgrade to MonitorControl.app v3.1.1 (Build 3096) has same symptom.

Everything worked prior to 2022-005 Catalina security-patch upgrade and Safari 13.x --upgrade_to--> 15.x. Constrast-slider stopped working after. Brightness and Volume controls work. Everything on AOC U3277WB monitor (same MacBook) works.

Another user reports similar behavior when upgrading macOS 12.5.4 -> 12.6 on a LG 32BL95-U-W 4K monitor.

Expected behavior

Contrast-changing slider should work.

Anything else?

No response

Environment Information (please complete the following information)

MonitorControl.app v4.1.0

system version (edited 2022-09-21 after 2022-005 Catalina security-patch upgrade):

$ sw_vers
ProductName:	Mac OS X
ProductVersion:	10.15.7
BuildVersion:	19H2026
$

Originally created by @johnnyutahh on GitHub (Sep 20, 2022). Original GitHub issue: https://github.com/MonitorControl/MonitorControl/issues/1182 ### Before opening the issue, have you...? - [X] Searched for existing issues - [X] Read through [the Monitor-Troubleshooting Wiki](https://github.com/MonitorControl/MonitorControl/wiki/Monitor-Troubleshooting) - [X] Updated MonitorControl to the latest version (if applicable) ### Describe the issue LG HDR 4K monitor (LG 32UL500, full specs: https://i.imgur.com/uPQ2wFC.png; advanced settings: https://i.imgur.com/sj4ZV8X.png) Contrast-control slider stopped working after no other, apparent change in hardware or MonitorControl.app v4.1.0 app. Downgrade to MonitorControl.app v3.1.1 (Build 3096) has same symptom. Everything worked prior to [2022-005 Catalina security-patch upgrade](https://support.apple.com/en-us/HT213343) and Safari 13.x --upgrade_to--> 15.x. Constrast-slider stopped working after. Brightness and Volume controls work. Everything on AOC U3277WB monitor (same MacBook) works. Another user [reports](https://github.com/MonitorControl/MonitorControl/issues/1182#issuecomment-1253773608) similar behavior when upgrading macOS 12.5.4 -> 12.6 on a [LG 32BL95-U-W 4K monitor](https://github.com/MonitorControl/MonitorControl/issues/1182#issuecomment-1255127191). ### Expected behavior Contrast-changing slider should work. ### Anything else? _No response_ ### Environment Information (please complete the following information) MonitorControl.app v4.1.0 system version (edited 2022-09-21 after [2022-005 Catalina security-patch upgrade](https://support.apple.com/en-us/HT213343)): ```markdown $ sw_vers ProductName: Mac OS X ProductVersion: 10.15.7 BuildVersion: 19H2026 $ ```

gitea-mirror closed this issue

2026-05-05 06:30:39 -06:00

gitea-mirror commented

2026-05-05 06:30:42 -06:00

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@johnnyutahh commented on GitHub (Sep 20, 2022):

Noteworthy, between MonitorControl.app contrast-control (this issue, #1182) working and not working:

I upgaded from Safari 13.x to 15.x.
I UNsuccessfully ran the 2022-005 Catalina security-patch upgrade. (It hung in the process of upgrading, and I hard-power-cycled my MacBook, and the resulting bootup seems fine--outside of this contrast-no-longer-working issue--and SoftwareUpdate still says 2022-005 is not installed. Finishing this install is my best bet for potentially solving this MonitorControl.app issue.)

Additionally: I just uninstalled, downloaded, and reinstalled MonitorControl.app v4.1.0 and contrast-control is still broken.

@johnnyutahh commented on GitHub (Sep 20, 2022): Noteworthy, between MonitorControl.app contrast-control (this issue, #1182) working and not working: 1. I upgaded from Safari 13.x to 15.x. 2. I _UNsuccessfully_ ran the [2022-005 Catalina security-patch upgrade](https://support.apple.com/en-us/HT213343). (It hung in the process of upgrading, and I hard-power-cycled my MacBook, and the resulting bootup seems fine--outside of this contrast-no-longer-working issue--and SoftwareUpdate still says 2022-005 is not installed. Finishing this install is my best bet for potentially solving this MonitorControl.app issue.) Additionally: I just uninstalled, downloaded, and reinstalled MonitorControl.app v4.1.0 and contrast-control is still broken.

gitea-mirror commented

2026-05-05 06:30:44 -06:00

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@waydabber commented on GitHub (Sep 21, 2022):

Does brightness and volume control work over DDC?
Does contrast control with older versions of the app?

@waydabber commented on GitHub (Sep 21, 2022): - Does brightness and volume control work over DDC? - Does contrast control with older versions of the app?

gitea-mirror commented

2026-05-05 06:30:46 -06:00

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@johnnyutahh commented on GitHub (Sep 21, 2022):

Does brightness and volume control work over DDC?

Yes.

Does contrast control with older versions of the app?

Unkown. I'll try this later.

I'll also test to see if the monitor's hardware control can adjust it's contrast.

(I'm away from the monitor right now)

@johnnyutahh commented on GitHub (Sep 21, 2022): > * Does brightness and volume control work over DDC? Yes. > * Does contrast control with older versions of the app? Unkown. I'll try this later. I'll also test to see if the monitor's hardware control can adjust it's contrast. (I'm away from the monitor right now)

gitea-mirror commented

2026-05-05 06:30:48 -06:00

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@mjnohai commented on GitHub (Sep 21, 2022):

This also happened to me when I upgraded from macOS 12.5.4 -> 12.6.

@mjnohai commented on GitHub (Sep 21, 2022): This also happened to me when I upgraded from macOS 12.5.4 -> 12.6.

gitea-mirror commented

2026-05-05 06:30:50 -06:00

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@johnnyutahh commented on GitHub (Sep 21, 2022):

MonitorControl.app v3.1.1 (Build 3096) has same problem in all above and below scenarios.
I successfully finished the 2022-005 Catalina security-patch upgrade install... but have same (problematic) no-constrast-control symptom.
LG monitor contrast control works when not plugged into MacBook. After plugging into MacBook the hardware-based contrast-control widget/slider "greys out"/becomes_disabled.

Anything else to check?

Current system state (after above upgrade):

$ sw_vers
ProductName:	Mac OS X
ProductVersion:	10.15.7
BuildVersion:	19H2026
$

@johnnyutahh commented on GitHub (Sep 21, 2022): 1. MonitorControl.app v3.1.1 (Build 3096) has same problem in all above and below scenarios. 2. I successfully finished the [2022-005 Catalina security-patch upgrade](https://support.apple.com/en-us/HT213343) install... but have same (problematic) no-constrast-control symptom. 3. LG monitor contrast control works when not plugged into MacBook. After plugging into MacBook the hardware-based contrast-control widget/slider "greys out"/becomes_disabled. Anything else to check? Current system state (after above upgrade): ``` $ sw_vers ProductName: Mac OS X ProductVersion: 10.15.7 BuildVersion: 19H2026 $ ```

gitea-mirror commented

2026-05-05 06:30:52 -06:00

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@johnnyutahh commented on GitHub (Sep 21, 2022):

Additionally:

I (re)restarted macOS (after 2022-005 Catalina security-patch upgrade successful install), same problem.
I (re)upgrade to MonitorControl.app v4.1.0, same problem.

Brightness and Volume sliders work; Constrast (slider) does not.

@johnnyutahh commented on GitHub (Sep 21, 2022): Additionally: 1. I (re)restarted macOS (after [2022-005 Catalina security-patch upgrade](https://support.apple.com/en-us/HT213343) successful install), same problem. 2. I (re)upgrade to MonitorControl.app v4.1.0, same problem. Brightness and Volume sliders work; Constrast (slider) does not.

gitea-mirror commented

2026-05-05 06:30:55 -06:00

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@johnnyutahh commented on GitHub (Sep 21, 2022):

Contrast slider (and Brightness slider, fwiw; I didn't test if the Volume slider affects behavior because I don't care about it right now) does work on above MacBook (macOS v10.15.7, build 19H2026) with an AOC U3277WB monitor.

Thus far only the LG HDR 4K monitor has a constrast-slider-failure symptom.

ALSO... I recall (before the 2022-005 Catalina security-patch upgrade) said LG monitor being listed as some specific model ID/number other than a generic "LG HDR 4K" ID. Hmmmm.

@johnnyutahh commented on GitHub (Sep 21, 2022): Contrast slider (and Brightness slider, fwiw; I didn't test if the Volume slider affects behavior because I don't care about it right now) _does_ work on above MacBook (`macOS v10.15.7, build 19H2026`) with an AOC U3277WB monitor. Thus far only the LG HDR 4K monitor has a constrast-slider-failure symptom. ALSO... I recall (before the [2022-005 Catalina security-patch upgrade](https://support.apple.com/en-us/HT213343)) said LG monitor being listed as some specific model ID/number other than a generic "LG HDR 4K" ID. Hmmmm.

gitea-mirror commented

2026-05-05 06:30:58 -06:00

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@johnnyutahh commented on GitHub (Sep 21, 2022):

Update: the AOC U3277WB Volume slider (as well as Brightness and Contrast slider) does work, just now tested it (with and audio sample).

@johnnyutahh commented on GitHub (Sep 21, 2022): Update: the AOC U3277WB Volume slider (as well as Brightness and Contrast slider) _does_ work, just now tested it (with and audio sample).

gitea-mirror commented

2026-05-05 06:31:01 -06:00

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@johnnyutahh commented on GitHub (Sep 21, 2022):

The problematic monitor is (apparently) an LG 32UL500. Here's photo of the back of said monitor with all the specs: https://i.imgur.com/uPQ2wFC.png

@johnnyutahh commented on GitHub (Sep 21, 2022): The problematic monitor is (apparently) an LG 32UL500. Here's photo of the back of said monitor with all the specs: https://i.imgur.com/uPQ2wFC.png

gitea-mirror commented

2026-05-05 06:31:03 -06:00

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@johnnyutahh commented on GitHub (Sep 21, 2022):

This also happened to me when I upgraded from macOS 12.5.4 -> 12.6.

@mjnohai - for which monitor(s) did you have a Contrast-control-slider-not-working problem?

@johnnyutahh commented on GitHub (Sep 21, 2022): > This also happened to me when I upgraded from macOS 12.5.4 -> 12.6. @mjnohai - for which monitor(s) did you have a Contrast-control-slider-not-working problem?

gitea-mirror commented

2026-05-05 06:31:06 -06:00

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@johnnyutahh commented on GitHub (Sep 21, 2022):

The problematic monitor is (apparently) an LG 32UL500. Here's photo of the back of said monitor with all the specs: https://i.imgur.com/uPQ2wFC.png

The LG 32UL500 display advanced settings: https://i.imgur.com/sj4ZV8X.png
the checkboxes in (1.) (above) previously had a blue background, now they have a white background (in just the checkboxes... as shown in the above screenshot). That's a little weird and I thought it worth noting.

@johnnyutahh commented on GitHub (Sep 21, 2022): > The problematic monitor is (apparently) an LG 32UL500. Here's photo of the back of said monitor with all the specs: https://i.imgur.com/uPQ2wFC.png 1. The LG 32UL500 display advanced settings: https://i.imgur.com/sj4ZV8X.png 2. the checkboxes in (1.) (above) previously had a blue background, now they have a white background (in just the checkboxes... as shown in the above screenshot). That's a little weird and I thought it worth noting.

gitea-mirror commented

2026-05-05 06:31:08 -06:00

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@johnnyutahh commented on GitHub (Sep 21, 2022):

More updates:

the checkboxes in (1.) (above) previously had a blue background, now they have a white background (in just the checkboxes... as shown in the above screenshot). That's a little weird and I thought it worth noting.

a. The blue-background checkmarks are back (in v4.1.0 after I downgraded to v3.1.1 re-upgraded bac tl v4.1.0).

b. I have edited the first post in this issue thread to include all the pertinent (I hope) info from the successive replies.

@johnnyutahh commented on GitHub (Sep 21, 2022): More updates: > 2. the checkboxes in (1.) (above) previously had a blue background, now they have a white background (in just the checkboxes... as shown in the above screenshot). That's a little weird and I thought it worth noting. a. The blue-background checkmarks are back (in v4.1.0 after I downgraded to v3.1.1 re-upgraded bac tl v4.1.0). b. I have edited the [first post in this issue thread](https://github.com/MonitorControl/MonitorControl/issues/1182#issue-1378658466) to include all the pertinent (I hope) info from the successive replies.

gitea-mirror commented

2026-05-05 06:31:11 -06:00

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@johnnyutahh commented on GitHub (Sep 22, 2022):

Please note: I plan to be away from the the above, problematic monitor (and therefore not able to test it) for about 8 days (reconnecting with it FriSep30), starting in about 1.5 hours. If anyone would like me to perform additional tests, pls reach me in (at least) the next 90 mins. :-)

@johnnyutahh commented on GitHub (Sep 22, 2022): Please note: I plan to be away from the the above, problematic monitor (and therefore not able to test it) for about 8 days (reconnecting with it FriSep30), starting in about 1.5 hours. If anyone would like me to perform additional tests, pls reach me in (at least) the next 90 mins. :-)

gitea-mirror commented

2026-05-05 06:31:13 -06:00

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@mjnohai commented on GitHub (Sep 22, 2022):

Sorry for the late reply, I have two LG 32BL95-U-W 4K monitors. I didn't see the issue you saw where the checkboxes became grayed out though.

@mjnohai commented on GitHub (Sep 22, 2022): > Sorry for the late reply, I have two LG 32BL95-U-W 4K monitors. I didn't see the issue you saw where the checkboxes became grayed out though.

gitea-mirror commented

2026-05-05 06:31:15 -06:00

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@johnnyutahh commented on GitHub (Sep 22, 2022):

Update: change in plans: I will have the problematic monitor available to me until approx 1pm EDT tomorrow (FriSep23).

Please note: I plan to be away from the the above, problematic monitor (and therefore not able to test it) for about 8 days (reconnecting with it FriSep30), starting in about 1.5 hours. If anyone would like me to perform additional tests, pls reach me in (at least) the next 90 mins. :-)

@johnnyutahh commented on GitHub (Sep 22, 2022): Update: change in plans: I will have the problematic monitor available to me until approx 1pm EDT tomorrow (FriSep23). > Please note: I plan to be away from the the above, problematic monitor (and therefore not able to test it) for about 8 days (reconnecting with it FriSep30), starting in about 1.5 hours. If anyone would like me to perform additional tests, pls reach me in (at least) the next 90 mins. :-)

gitea-mirror commented

2026-05-05 06:31:17 -06:00

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@johnnyutahh commented on GitHub (Sep 26, 2022):

Is there any other exploration (info gathering, debugging, etc) that I/we can do on this besides testing other monitors?

@johnnyutahh commented on GitHub (Sep 26, 2022): Is there any other exploration (info gathering, debugging, etc) that I/we can do on this besides testing other monitors?

gitea-mirror commented

2026-05-05 06:31:19 -06:00

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@waydabber commented on GitHub (Sep 26, 2022):

Hey @johnnyutahh - can you try BetterDisplay as a test and see if contrast control works with that app or not. As an alternative you can try m1ddc as well.

@waydabber commented on GitHub (Sep 26, 2022): Hey @johnnyutahh - can you try [BetterDisplay](https://betterdisplay.pro) as a test and see if contrast control works with that app or not. As an alternative you can try [m1ddc](https://github.com/waydabber/m1ddc) as well.

gitea-mirror commented

2026-05-05 06:31:21 -06:00

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@johnnyutahh commented on GitHub (Oct 4, 2022):

Hey @johnnyutahh - can you try BetterDisplay as a test and see if contrast control works with that app or not. As an alternative you can try m1ddc as well.

Thanks @waydabber. Unfortunately...

BetterDisplay does.not.run/is.not.supported on my Catalina OS (according to my first install try).
m1ddc build fails (not sure this is the correct way to install it...? I did not spend much time looking) possibly for similar/same core obstacle/reason(s) as BetterDisplay (this is only speculation of course), details below.

$ gitinfo
  Fetch URL: https://github.com/waydabber/m1ddc.git
  Push  URL: https://github.com/waydabber/m1ddc.git
7d6760a6175311f81a1940e30f5763f08a4b160a
$ make
clang -fmodules -o m1ddc m1ddc.m
m1ddc.m:84:63: error: use of undeclared identifier 'kIOMainPortDefault'
            io_registry_entry_t root = IORegistryGetRootEntry(kIOMainPortDefault);
                                                              ^
1 error generated.
make: *** [all] Error 1
$ date
Tue Oct  4 11:28:15 EDT 2022
$ sw_vers
ProductName:	Mac OS X
ProductVersion:	10.15.7
BuildVersion:	19H2026
$
$ alias gitinfo
alias gitinfo='giturls ; gitcurrentsha'
$ alias giturls
alias giturls='git remote show origin | grep URL'
$ alias gitcurrentsha
alias gitcurrentsha='git rev-parse HEAD'
$

ps. I'm also noticing... you (@waydabber) appear to be the sponsor/author of the above things -- thank you!

@johnnyutahh commented on GitHub (Oct 4, 2022): > Hey @johnnyutahh - can you try [BetterDisplay](https://betterdisplay.pro) as a test and see if contrast control works with that app or not. As an alternative you can try [m1ddc](https://github.com/waydabber/m1ddc) as well. Thanks @waydabber. Unfortunately... 1. BetterDisplay does.not.run/is.not.supported on my Catalina OS (according to my first install try). 2. `m1ddc` build fails (not sure this is the correct way to install it...? I did not spend much time looking) possibly for similar/same core obstacle/reason(s) as BetterDisplay (this is only speculation of course), details below. ``` $ gitinfo Fetch URL: https://github.com/waydabber/m1ddc.git Push URL: https://github.com/waydabber/m1ddc.git 7d6760a6175311f81a1940e30f5763f08a4b160a $ make clang -fmodules -o m1ddc m1ddc.m m1ddc.m:84:63: error: use of undeclared identifier 'kIOMainPortDefault' io_registry_entry_t root = IORegistryGetRootEntry(kIOMainPortDefault); ^ 1 error generated. make: *** [all] Error 1 $ date Tue Oct 4 11:28:15 EDT 2022 $ sw_vers ProductName: Mac OS X ProductVersion: 10.15.7 BuildVersion: 19H2026 $ $ alias gitinfo alias gitinfo='giturls ; gitcurrentsha' $ alias giturls alias giturls='git remote show origin | grep URL' $ alias gitcurrentsha alias gitcurrentsha='git rev-parse HEAD' $ ``` ps. I'm also noticing... you (@waydabber) appear to be the sponsor/author of the above things -- thank you!

gitea-mirror commented

2026-05-05 06:31:24 -06:00

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@johnnyutahh commented on GitHub (Oct 18, 2022):

Misc update:

Above LG monitor continues to be Contrast-control-broken problematic.
U3277WB monitors DO work okay, details in screenshot below.
A separate and different LG monitor (from the one describted above that's Contrast-control broken) does seem to fully function (inlucing Contrast control), but I do not have said LG monitor immediately available, I'm only going from memory, and I'll try to get the details later (but won't have access to the working LG monitor for at least a week).

@johnnyutahh commented on GitHub (Oct 18, 2022): Misc update: 1. Above LG monitor continues to be Contrast-control-broken problematic. 2. U3277WB monitors DO work okay, details in screenshot below. 3. A _separate_ and different LG monitor (from the one describted above that's Contrast-control broken) _does_ seem to fully function (inlucing Contrast control), but I do not have said LG monitor immediately available, I'm only going from memory, and I'll try to get the details later (but won't have access to the working LG monitor for at least a week). ![2022-10-18-MonitorControl-U3277WB-display-settings-screenshot](https://user-images.githubusercontent.com/8906609/196534736-54044e28-030c-4802-bcec-4b7816942f39.jpg)

gitea-mirror commented

2026-05-05 06:31:25 -06:00

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@johnnyutahh commented on GitHub (Oct 26, 2022):

Update: I returned the problematic monitor, and can no longer perform tests on said united/model/hardware.

@johnnyutahh commented on GitHub (Oct 26, 2022): Update: I returned the problematic monitor, and can no longer perform tests on said united/model/hardware.

gitea-mirror commented

2026-05-05 06:31:28 -06:00

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@waydabber commented on GitHub (Nov 14, 2022):

All right, thanks @johnnyutahh for the info and sorry about the lackluster handling of the problem on our part!

@waydabber commented on GitHub (Nov 14, 2022): All right, thanks @johnnyutahh for the info and sorry about the lackluster handling of the problem on our part!

gitea-mirror referenced this issue

2026-05-05 07:06:50 -06:00

[PR #690] [MERGED] Better simplified Chinese translation. #1177

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[GH-ISSUE #1182] LG HDR 4K monitor Contrast-control slider stopped working (no change in hardware or MonitorControl.app) #690

Before opening the issue, have you...?

Describe the issue

Expected behavior

Anything else?

Environment Information (please complete the following information)