Yeah, my experience with Aqara has been like that: flawless out of the box, pairs quickly with no issues, reports state correctly, all good. Then after a random while (at least a few hours, but within a day) they just drop off the network never to be seen again until I re-pair them.
I even got an Aqara smart plug just to act as a router and pair the Aqara stuff through it, it was better but this time it dropped off after a few weeks. Might’ve been the battery though, it was a temperature sensor in -20°C.
Saw them last year with Kamelot, it was an amazing show. I didn’t know them before but I’m a fan now!