Glad you found the issue. Zigbee mesh issues can be hard to troubleshoot since so many other devices use 2.4 ghz. A wifi router close to the hub can cause a problem, a conflicting zigbee mesh like Hue, a 2.4 ghz wireless phone, etc.
This thread is a little old, but if you are still watching, could you share what repeaters you used? I’m having the same problem and want to make sure i don’t waste money on things that won’t work