LG Ultrafine Brightness Dimmed when wake from sleep

I had the same problem after upgrading to Monterey. Updated the LG 5k firmware and was all sorted.

https://www.lg.com/us/support/software-firmware-drivers?customerModelCode=27MD5KA-B&csSalesCode=27MD5KA-B.AUS&category=CT10000030&subcategory=CT30014440

re-posting because of typos

"The LG screen manager app also told me I was running the latest firmware only to go to the LG firmware website (the link I shared) and find firmware as recent as 10 Jan 2022. Humor me. Install the firmware and observe "

The app also told me I was running the lates up only to go to then LG firmware website (the link I shared) and find firmware as recent as 10 Jan 2022. Humor me. Install the firmware and observe

I just bought a 27" LG 27MD5KL monitor for my 16" MacBook Pro 2021 M1. I'm having the same issue. When I wake the monitor from sleep, it's dimmer than its pre-sleep full brightness setting. Aside from that, the monitor is superb and works with the Mac really well.

I do use an Apple Magic Keyboard via Bluetooth, so I'll try the workaround others have suggested -- tap the F1 or F2 key to get the brightness back up.

Up until now, I've been going into Display Preferences and clicking the Brightness slider, which also bumps the brightness back up to full. Total pain, but at least it's not rage-inducing.

I'm guessing nobody from Apple reads these posts, so I'd suggest everyone submit a bug report via the Apple site:

https://www.apple.com/feedback/macos.html

Happy Mac-ing.

Sorry. Follow this one https://www.lg.com/us/support/software-firmware-drivers

then there is a search box for finding softwares and firmware by model. Search for 27MD5KL-B.

The firs result that pops up is the one for Mac OS

Fastest method for me is to do a quick toggle between brightness up and brightness down keys (or vice versa).

Another issue that I've begun having (I use two LG 27 5K displays is that sometimes (usually after waking from sleep mode), I can only control the brightness of one of the two displays. Unplugging and replugging the problematic display usually fixes the issue.

Yep. Tapping the F1 or F2 brightness keys seems to do the reset trick.

If anyone else is having this problem, please submit a bug report to Apple:

https://www.apple.com/feedback/macos.html

Same here, M1 Air. I use a magic keyboard, and the brightness keys on the magic keyboard for some reason control the LG display, while the keys on the Mac control the built in display -- so it's slightly simpler to turn the LG brightness back up after waking the displays.

Same issue here with 2xLG 5k. My previous 2018 i9 MBP didn't have the issue but the 16" M1 does about 50% of the time. Someone mentioned audio issues but I've not had any troubles with that.

Something I discovered is that on the i9 you can use the modifiers (can't remember if Option or Command) with the brightness controls on the Apple keyboard to change the brightness of the two LG screens, however on the M1 computers you just need to click anywhere on the respective screen and then the brightness control works on that specific screen.

Hoping Apple notices this thread and includes a patch in a future update, it's not a huge issue but it's a bit annoying.

Unfortunately the latest Monterey update (12.3.1) did not fix the issue. I had a little hope as there were fixes for other external monitor bugs... just not this one I guess. But I figured it would not be the case as LG told me this is an issue on their end with Monterey and needing to do a firmware update to the monitor at some unspecified time. Come on guys Monterey has been out for how many months now??

Gotta say I'm pretty close to dropping the $4k on a couple Apple Studio Monitors just to get out of the LG business... my 2 UltraFines were buggy right out of the gate and 5 years later here I am... still dealing with bugs.

I'd recommend submitting a bug report to Apple. I'm assuming they spend 0 minutes on these discussion forums.

Feedback - macOS - Apple

I've submitted a bug report for this LG display issue several times already, so I hope others will too.

This is such a pain. My current workaround is to use Brightness-Sync ( https://github.com/OCJvanDijk/Brightness-Sync/releases )

and after each wake, reduce and increase the brightness.

I have the same issue. I'm running two 27" LG Ultrafine displays on my 16" M1 MacBook Pro, and both displays behave the same way. I also use a Magic Keyboard, so I can click the "brightness up" and then the "brightness down" keys and it gets me back to the appropriate brightness level, but I'm still hoping this gets fixed in the next Monterey update.

I have an LG Ultrafine 4K, which I bought with an Intel Mac mini, and I didn't have this problem until I swapped in an M1 Mac mini. I have had the same issue with other M1 Macs, including a MacBook Air. My research leads me to conclude this is an M1-specific problem that Apple and LG must be aware of but can't be bothered to fix.