Cannot control brightness - LG Ultrafine 4K

Hi Reader2,

Thanks for reaching out in Apple Support Communities. I understand you're unable to adjust the brightness on your LG Ultrafine 4K monitor that you're using with your MacBook Pro and you have been able to adjust the brightness with the methods you mentioned before. I know it's important to be able to adjust the display you're working with; I'd like to help. If you haven't already, I'd suggest using these steps to start your Mac in safe mode and test for the issue: How to use safe mode on your Mac

After using safe mode, restart your Mac normally and test for the behavior again. If the behavior continues after using safe mode, use the steps in the following resources to reset the NVRAM and SMC on your Mac; this will reset the video ports on your Mac:

• Reset NVRAM or PRAM on your Mac
• How to reset the SMC of your Mac

Let me know what you find.

Best Regards.

Are you sure this unspecified LG display device supports this feature?

Buried in the bottom of a review of the LG 34WK95U, there’s this, highlight added:

Who this is not for?

In short, regular consumers. End users that want a replacement monitor or main screen to house a plug and play macOS friendly all-in-one display in the UltraWide aspect, this is not for you. Using the TB3 uplink , there is no audio control from your Mac. No brightness control either. No FaceTime camera. Tinny sound and no microphone. These factors make this an unsatisfying option for a Mac mini or a MacBook.

Hi Reader2,

Thanks for letting us know you've tried those steps. At this point, I'd recommend reaching out to Apple for additional assistance: Get Support

Best Regards.