HDR Monitors don't adjust brightness independently.

[corndog2000]

GPU: AMD RX 9070XT
GPU Driver version: 26.6.1
OS: Windows 11 25H2
Monitorian version: 4.14.0.0

These are my monitor names in the app.

Almost every time I try adjusting the LG ULTRAGEAR+ monitor brightness the LG ULTRAGEAR monitor also adjusts to the same brightness level. But, if I do the opposite and adjust the LG ULTRAGEAR monitor then the LG ULTRAGEAR+ doesn't update.

BKAUhbS5Ut.mp4

[emoacht]

Thank you for reporting.
I have no idea what is going on but could you post probe.log and operation.log? How to produce these logs is explained in Reporting section of readme.

[corndog2000]

probe.log

Here is probe.log. I'll upload operation.log when I get enough data.

[corndog2000]

Here is the operation log. The issue started happening again after I started using my computer around 18:36:52. I set the LG ULTRAGEAR+ monitor resolution a bunch to hopefully populate the log enough. Every time it also set the LG ULTRAGEAR monitor to the same brightness level.

operation.log

[emoacht]

Thank you for the logs. So they are set to use HDR.
Does it happen consistently, or only occasionally?

[corndog2000]

This happens occasionally. It seems to start happening when I lock my computer and return to it later. Although, it also seems to require me to leave it locked for hours before this bug happens.

[emoacht]

I see. Restarting this app after locked makes a difference?

[corndog2000]

Restarting the app once it's in the bugged state does resolve the issue.

[emoacht]

To recap, here is where I currently stand.

• This behavior occurs specifically on HDR enabled monitors. The way to get/set their brightness (SDR white level) is completely different from DDC/CI and Microsoft provides no official documentation on this.
• It is unlikely that monitor names are relevant here, as they are not used to identify each monitor.
• To get/set SDR white level of a specific monitor, a set of ids is used. This set of ids is designed to be replaced with the latest one, including after resumed. Therefore, restarting this app should not cause any difference in behavior.
• In conclusion, I am still unable to determine the exact cause of this issue.

That said, to aid in debugging, I added this set of ids in the log.