Screen brightness changing when waking from sleep

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Level 1

32 points

Screen brightness changing when waking from sleep

Hi, I am having an odd issue with a Mac Studio Max, 32core GPU 64gb ram , 2tb ssd, and my LG 27" Ultrafine 5k display.

When the computer wakes from sleep, the brightness of the LG display changes. I am fully color managed (using BasICColor Display 6) and the display is set to 120cd/m brightness through profiling. When I wake the Mac Studio up from sleep, the brightness is boosted up to around 200 cd/m consistently.

I do not have nightshift on and I have disabled the F1 and F2 brightness functions on the keyboard so that I don't inadvertently change the brightness while using the keyboard so this would seem to be some hiccup either with the OS or the Mac Studio.

I am also using a BenQ SW321C display that does not change brightness when the computer wakes up... so one display is working great and is staying consistent brightness-wise, the other is shifting upon wakeup.

The only variance with the LG is the brightness, there is no color shift so I'm not thinking it is an issue with the display. When it is awake there is no shift to the brightness once it is reset to the proper level, but as soon as it sleeps and wakes up, it is brighter again.

I have tried a new Thunderbolt 3 cable, switched thunderbolt ports, restarted everything, turned off, unplugged and replugged the LG display and no luck finding a fix.

Prior to getting the Mac Studio I was using the LG with a 2019 iMac 5k and it worked reliably and I never had this issue... so maybe an M1 thing? Any thoughts??

Mac Studio, macOS 12.3

Posted on Mar 24, 2022 6:57 AM

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Answer 1

Mar 30, 2022 1:06 PM in response to photogFG

That is a known problem with the M1 and the UltraFine. I found that on wake the M1 will send a command to set brightness to 200 nits. You will find this in the console log. I have opened a couple tickets with Apple. First they said it was an issue with the monitor. Then they said they would send it to engineering. Then closed the ticket as unsupported.

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Answer 2

mwrourke

Level 1

4 points

May 7, 2022 2:41 PM in response to mwrourke

Note also that this behaviour only seems to occur if the LG Ultrafine is designated the "Main display" (as configured in System Preferences). So if you have two monitors, and one isn't an LG Ultrafine, this may be a work around.

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Answer 3

May 7, 2022 3:01 PM in response to mwrourke

mwrourke wrote:

Note also that this behaviour only seems to occur if the LG Ultrafine is designated the "Main display" (as configured in System Preferences). So if you have two monitors, and one isn't an LG Ultrafine, this may be a work around.

That's interesting!

If true, that might be a bug left over from MacBooks, to brighten the built-in display on wake-up.

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Answer 4

mwrourke

Level 1

4 points

Apr 29, 2022 7:53 PM in response to photogFG

I have the same problem. Mac Studio with LG Ultrafine 5k monitor. MacOS 12.3.1 Monterey.

It appears the saved brightness setting isn't lost on wake - just not used, because if I type F1 then F2 (decrease then increase brightness) (or F2 then F1) the old level appears to be restored.

This isn't acceptable behaviour.

I have raised a support ticket with Apple and escalated for engineering response.

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Answer 5

May 2, 2022 5:39 PM in response to photogFG

Hello, I also have the same problem, I have a MacMini M1 and an LG Ultrafine 4K monitor, I use the brightness to 30% regularly, when the mac wakes up after sleeping due to inactivity it raises the brightness to almost 50%, when I press the F1 or F2 it sharply adjusts to the previously established value, I expect an update with the correction of that error.

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Answer 6

May 3, 2022 6:16 AM in response to carlosoonline

carlosoonline wrote:

...

I expect an update with the correction of that error.

You won't get that just from posting here.

Readers are almost all other Users like you. Apple does not troll the forums looking for complaints.

Call Apple support, work through the simple steps with the first responder, then ask that your problem be escalated to a specialist. The specialist should create a formal Bug Report, or add you voice to an existing Bug report, increasing its urgency.

Get Support

.

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Answer 7

mwrourke

Level 1

4 points

May 9, 2022 2:14 PM in response to Grant Bennet-Alder

I can confirm that the brightness is much less likely to be messed up if the display isn't the "Main Display", but it still can occur. It may relate to the depth of sleep involved. I'm finding the display is ok after a short sleep, but not after an overnight one.

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Answer 8

May 7, 2022 3:09 PM in response to mwrourke

I have two LG Ultrafine 5Ks connected to my Studio and yes, the "main" display is the one that acts up most of the time. Strange is that the secondary display sometimes changes after sleep also.

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Answer 9

tbirdvet

Level 6

17,048 points

Mar 25, 2022 1:55 PM in response to photogFG

I have an LG 5k display. When used with my MBA M1 when waking from sleep it is at a lower brightness than it was before sleeping. When I use the same display with my Mac Mini M1 the brightness never changes so not sure what is happening here.

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Answer 10

tbirdvet

Level 6

17,048 points

Apr 16, 2022 3:36 AM in response to tbirdvet

Well for some reason now my Mac Mini M1 has this issue. Every time it wakes from sleep it has a lower brightness than before sleep so does not remember the setting. I have seen that checking the box to auto adjust in the display pane helps somewhat but not really a solution.

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Screen brightness changing when waking from sleep

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