Did you try the double-secret-probation pairing trick that @kkossev has talked about? (The "trick" was possibly created by someone else, can't remember...)
Found it!
…the ‘double luck’ procedure worked for me and for some other HE users who tried it. I was able to pair and keep connected some very problematic Zigbee devices that never worked before on my C-8 hubs.
From https://community.hubitat.com/t/2-3-9-157-zigbee-plugs-are-found-but-do-not-function/139919/35
1. Bring the device right next to the hub
2. Go to Settings->Zigbee Details and click the 'Rebuild Network' button.
3. Wait for the process to finish (the button will become enabled again)
4. Click the same 'Rebuild Network' button again, and wait for the process to finish.
5. Go to Devices -> Add Device -> Zigbee and click on the 'Pair while trying to avoid Zigbee 3.0 repeaters ' link, confirm.
6. Start the Zigbee pairing on the device (press the pairing button for 4-5 seconds).
Please follow the steps 1..5 precisely, not skipping and not adding anything else.
From
