I have had a somewhat odd experience in the last week. The master bedroom has 4 devices:
2x Philips Hue bulbs
1 GE dimmer switch
1 GE fan controller
I have an Alexa group that puts the Hue bulbs and dimmer switch together for the room control. When I was in there the other day, I kept telling Alexa "Set master bedroom to 50%", and the 2 Hue bulbs would respond, but the ceiling light would stay off.
After some trial and error, I found that the dimmer switch appeared to be non-responsive to set level requests (set to 1%, 50%, etc.), but would respond to simple on/off ("turn master bedroom on"). Not sure what happened there, but it still shows up as a dimmer switch in Hubitat, thought it maybe got changed to a standard toggle switch or something, but no dice.
Try turning off breaker on switch for a few minutes and back on. GE switches sometimes stop responding and this fixes it. I just went through this with my father for a switch at his house.
But it is odd that it's just not responding to Alexa for setting the dimmer level, it can still turn it on and off, and I believe set level still works from within Hubitat (but I'll have to confirm that later). Just really weird!
That said, with GE switches specifically, the airgap isn’t always enough to fully reboot the switch. So with this brand specifically, if you’re having trouble getting it to respond when it used to work just fine, trying turning off the current at the circuit breaker and then restoring it. That’s often enough to solve the last connection problem.