With this driver, it means it probably fell off your Zigbee network (or hasn't checked in for some other reason, perhaps a dead battery or being outside your mesh range). The solution is generally to re-pair in that case. Don't delete it from Hubitat first; just put the device in pairing mode and put Hubitat in Zigbee pairing mode, too, and it should be (re)discovered as the same device.
If this keeps happening, Xiaomi/Aqara devices are known to be picky about what Zigbee repeaters you use. This thread is a must-read:
