For the last several months I have been having Zigbee devices stop responding. This was especially true with my 17 Keen smart vents. I have spent time nearly every day going around to Zigbee devices, factory resetting them, running add a device (any of 3 methods - no difference), the devices rejoin as expected and then MIGHT work.
I have rebooted my Zigbee hub, I have reset the Zigbee radio and network and have "rebuild" checked on reboot. And I have monitored the "map" of Zigbee devices.
I have seen some "weirdness" on the map, last night there was a device with just a device ID but no name and clicking it did NOT take me to the device page. I did not capture that at the time - sorry.
Last weekend I shut down my entire network to include powering off my entire house (clearing Zigbee repeaters in outlets/switches). I brought my zigbee hub up to check my network (battery devices) all of which were connected direct to hub (as expected). Then I brought up all my powered devices and let things settle.
The next day I started attacking devices that had no activity - manually rejoining them and wash rinse repeat. But this behavior continues. It feels like when I join one device it disables another device. I have one Sengled color bulb I am working with now. If I factory reset it then start Zigbee pairing it will be found - but other devices also show up as found previously connected devices as well - not every time, but sometimes.
I have this bulb - Garage Lamp - sitting 8 feet from zigbee hub and have reset it and rejoined it a couple times today. It will join and usually works. But if I reset the Zigbee radio or rebuild the network it stops working. AND I just caught it on the map being BLUE which we know "bulbs" suck as repeaters. It has an orange connection to the hub, but it also has green route to another device.
Not that this is any comforting that your experience could improve, but I've had the same experience with Keen vents a long time ago and the only solution was to give up on them. With that being said Sengled bulbs and Keen vents require good repeaters. I generally recommend one repeater for every 6 battery operated devices, some cases may require more repeaters depending on the building materials, obstacles between your vents and distance.
And yes, I want to give up on Keen - but I have 17 of them and I have yet to find another solution that actually works. I control them with Ecobee Suite Manager and when the vents are working they work great.
That said, I have had 4 vents fail/die where they just were not able to open/close and didn't even report obstruction - they just stopped moving and reported they were in % requested.
I switched to a Zoning panel with electronic dampers and 3 thermostats. Never been happier with the result, and probably the savings on replacing the batteries in the vents, paid for the zoning panel installation and thermostats
I had a lot of ZB issues when I moved from C7 to C8 (ZB was rock-solid on my C7)... A few things finally fixed it for me -- I of course can't guarantee any of this will help you, but it may give you some food-for-thought...
I went all ZB3.0 for my mains-powered repeating devices. Mercifully, I only had two ZB1.2 devices to remove (older Halo smoke detectors). I have quite a few repeaters spread out everywhere to ensure robust mesh coverage.
I dropped my ZB radio power down to 4, and moved channel from 15 to 25. My Hue is on 20, and my eero typically stays in the lower channels for 2.4, so that channel move helped a bit more with deconfliction. Anytime I've experimented with bumping the radio power back up, I get wierdness, so 4 is the magic number for me.
I've been looking at the map and watching on rebuilds. I was suspicious of a couple of "plug-in" modules and pulled them out today - one was centralite and has seemed reliable for years. This problem started just a couple months ago - timing may be close to when I replaced all my smart locks (5 of them) from BT to zigbee. Obviously they are not repeaters, but last night I was going back and forth with this one lamp and one lock, whenever I would reset the lamp the lock would also show up when I started join. Had same issue last week with a vent - once I reset this particular vent several other devices started behaving correctly.