Brightness Action Broken on Big Sur (M1)?

I'm running Keyboard Maestro 9.1 on Big Sur (M1, Apple Silicon). My "increase screen brightness" (and "decrease screen brightness") hotkey actions have stopped working. Ran great on Catalina.

When I trigger the "Increase Screen Brightness" action (or "try" it in the editor), it shows the on-screen pop-up as already being at full brightness, even if actual brightness is much less. Similarly, the "Decrease Screen Brightness" action always shows the on-screen pop-up as one-less-than full, regardless of where actual brightness is at. Neither action actually changes the brightness any longer.

Anyone else experiencing this?

Those actions simulate the hardware brightness keys, after which the system takes over and does its thing (or ignores the keystrokes).

How the system behaves is a bit of a mystery.

Your experience seems weird though since the system is clearly recognising the key, but then it seems like the brightness is being reset to full brightness all the time - perhaps there is some other process going on that is affecting the brightness?