Lyric T6 and Homekit

Good afternoon, all.

I have a very strange situation with a the Honeywell Lyric T6 and the Homekit integration. My home has two of these thermostats, one for the upper floors and one for the lower floors. Both had been integrated to Home Assistant through Homekit and working like a champ, until about a week ago when the upper floor thermostat dropped off. I’ve been unable to get it to reassociate.

The thermostat still shows up on the WiFi, it’s on the same subnet as Home Assistant, and I’ve tried explicitly removing the Homekit pairing on the thermostat and waiting for it to be rediscovered. No dice.

Through it all, the other thermostat has been working like a champ. It seems very bizarre that one of them would fail while the other wouldn’t. Is there anything I need to do on the HA side to be able to rediscover the thermostat? It almost feels like it’s still on an association list somewhere.