I have a Group-2.1 containing 4 Philips Hue bulbs, which are connected to my Hubitat C8 with the Hue Bridge Integration. The on, off, and setLevel commands work fine but startLevelChange doesn't do anything. The driver is Group Bulb Dimmer-2.1. Note that start and stopLevelChange works on the individual hue bulb devices.
I'm trying to have these lights controller by an Inovelli dimmer switch in smart bulb mode and that isn't working either. The on/off works but dimming doesn't.
Are these hue bulbs also in a group or zone on the hue bridge? If so, rather than use Hubitat group, you could just connect the dimmer switch to the hue group. startLevelChange should work on the Hue group (as least it does with my CoCoHue group).
Set the change level for a button Hold, and stop change level on Release.
I use the Adv. Hue Integration app, and had issues trying to control lights with a Phillips dimmer, due to how the Hue bridge controls the same lights with a Lutron Aurora rotary dimmer. At the moment I use a conditional rule in the buttons to check for both conditions to determine how to proceed (metioned for what it's worth, not suggesting you need to go that far).
This is correct, and is be surprised if the OP'S also didn't see an error in Logs when trying this with the built-in integration that would further pinpoint this as the problem (as the command does not exist, which you can also see on its device detail page).
The startLevelChange command exists on the individual Hue bulbs (and works) and it exists on a Group-2.1 group comprised of them. My expectation was a Group-2.1 startLevelChange command would work since it works on the underlying individual bulbs.
startLevelChange doesn't exist on the native Hue Group though, but i wasn't trying to use that initially.
I guess I was assuming it was a Hue group and not a Hubitat group of Hue bulbs (though even Hubitat groups didn't have this command until recently). The latter can be a recipe for disaster in any case with too many bulbs, so I hope not, but that's a different issue then.
Using a CoCoHue hue group and controlling that with a button controller is working. Reposting Button Controller config in case someone comes across this thread later:
