Hello @Helge_K, I wouldn’t have noticed that behavior so far. But first, I’m not using the Aqara TRV for too long. And second, my external temperature sensor (a group of sensors) keeps changing quite frequently (like every 5min or so).
I did notice that when the batteries are changed, the TRV falls back to the internal value. But my blueprint takes care of that. Every time the external temperature value is changed, the blueprint also checks if the TRV is still configured to receive an external value and if not, it configures it (again) before sending the changed temperature.
I have no experience with that Z2M extension you mentioned and don’t see any benefit using that solution if you already have HA running. I’d only see a benefit if there was a way to natively bind a ZigBee temperature sensor to the trv by using the ZigBee protocol so that it also works without a coordinator.