The ''Increase/Decrease Screen Brightness'' actions work on my Macbook, but not on an Apple Studio Display plugged into a Mac Studio. The Studio Display is the only monitor that is plugged in. Using the built in screen brightness buttons on the keyboard increases or decreases screen brightness (F1/F2), so why doesn't the KM action work?
Hey @andy,
Because? 
Keyboard Maestro Wiki ⇢ Screen Brightness Actions
“These actions are the same as pressing the hardware brightness buttons, with or without the option&shift key. They typically affect the primary screen only.”
But seriously – let's see if Peter will give you a more satisfactory answer.
-Chris
As @ccstone mentioned, the actions simply simulate the hardware keys - after that the system does whatever the system does which is beyond Keyboard Maestro’s ability to control.
At some point I will probably add more Display control options if I can, but these actions just simulate the hardware keys, so there is nothing I can tweak to adjust its behaviour.
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You can fix this by installing MonitorControl. Then the Apple Studio Display can be controlled with the hardware keys -- and thus with the KM action.
As an aside: I uses this because my keyword is a 3rd party one (Logitech MX keys) and it does not have the hardware keys -- but with KM plus MonitorControl I can simulate it.
Hi everyone, I didn't want to install another third party bit of software for this. What I found is that in macOS 15, you can go to System Settings > Keyboard > Keyboard Shortcuts > Display and set F1 and F2 to brightness up and down. I hadn't realised this was accessible from System Settings. Still not perfect because you can't hold the key down to increase all the way, but it is better than nothing!