I have two 100W-equivalent soft white-only hue bulbs, directly paired with the hub, and recently they both have begun to - randomly and not in unison - turn off and then back on again, then go to about 20% brightness. At which time, the bulb will become totally unresponsive for several minutes, and then eventually return to its previous state and become responsive again.
I've tried factory resets through the hue app (via bluetooth) to no avail.
I am not seeing any indication of activity with these devices in the logs when this happens, even with debug logs enabled.
Bulbs are on their latest firmware, hub is on the latest firmware.
What do the logs say when this happens? On their device pages what does it say "in use" by at the bottom? Are the ZLL 1.2 or 3.0 bulbs? What wifi channel is your router on, and what channel is zigbee on within Hubitat? Lastly do you have alexa? If so for giggles turn off hunches. (likely not it but it can't hurt)
I think you've got a couple of bad bulbs, maybe with a power supply issue. Those are the latest generation of Hue (Zigbee 3.0) so should work fine with Hubitat. I've got around 8-10 of the color version of those with a solid connection to Hubitat (with a bunch of Inovelli Zigbee 3.0 Switches that also help the mesh)
You wouldn't see anything in the logs or events if the bulbs are having this problem. To be completely certain, I'd do a factory reset on them and leave them connected on Bluetooth from your phone and see if they exhibit the same problem.
Interestingly, they came out with a firmware update for these bulbs very recently - 1.101.8 - I updated one bulb to that, and I'm going to see if that fixes it before doing more troubleshooting. No release notes yet on their website, and I've got $10 it's "bug fixes and performance improvements"
Well, it's still misbehaving, simply linked to the app via bluetooth and nothing else. I think what we've got here is a bulb gone bad. I'm going to toss it and replace it. Fortunately it's one of the white-only ones, so it's only $20.