Can't change display brightness after upgrading to Sonoma 14.4

[billibala]

I have 2 21.5" LG ultrafine 4k display (22MD4KA).

The only way to modify display brightness has always been... using the brightness keys on Magic Keyboard or from Control Center.

Since I upgraded to macOS Sonoma 14.4, the OS does not allow changing display brightness through "Settings" app, Control Center nor from keyboard.

Opening Control Center shows both brightness sliders disabled.

System Settings does not even show a brightness slider.

Everything was fine when my Mac Studio was running previous (14.3) Sonoma.

Did you run into similar problem?

Thanks
Bill

 

[billibala]

This should be a software bug.

If I disconnect one display, reboot the computer, brightness slider is back.

Now, reconnect the other display, the other display will have brightness slider disabled.

 

[bogdanw]

Free apps that might offer better brightness control:
BetterDisplay https://github.com/waydabber/BetterDisplay
MonitorControl https://github.com/MonitorControl/MonitorControl

 

[filmbuff]

I have the same monitor, and the same issue! Upgraded to 14.4 yesterday and it broke my brightness control, and also the audio. The monitor doesn't show up at all as an audio device and the sound plays over the laptop speakers. So far I tried unplugging and plugging the monitor into a different USB port, rebooting the laptop with and without the monitor plugged in, and I downloaded the LG screen control software which was totally useless. Seen a number of topics about this online but nobody has any solutions.

 

[billibala]

Could this issue just only be affecting the old 21.5" LG Ultrafine 4k display?

I imagine there will be more complaints/discussions if it's affecting the 27" LG 5k model as well.

 

[FNH15]

FYI My UltraFine 5K (original model) works fine in re: brightness control (I don’t use the built in speakers so I can’t comment on that).

 

[kitKAC]

Could this issue just only be affecting the old 21.5" LG Ultrafine 4k display?

I imagine there will be more complaints/discussions if it's affecting the 27" LG 5k model as well.

I noticed the greyed-out slider on my 2018 MacBook Pro the other day, and I don't use this machine with an external monitor at all. I can still change the brightness with the Touchbar and in System Settings though, only Control Centre is broken.

 

[flowrider]

My LG 24MD4KL-B Ultrafine is fine👍🏻



Lou

 

[billibala]

I think I have a workaround. Not sure if it helps anyone...

It seems that... if I unplug all USB devices which was originally connected to my 2 LG Ultrafine displays, connect those deices directly to the computer instead. Then, reboot the system. Monitor brightness sliders come back out again!

 

[city_17]

Same problem here. I installed the BetterDisplay app and that does allow me to change the brightness (this is for the 22MD4KA as well).