Have you tried powering down your hub, unplugging it at the wall, waiting a minute and then plugging back in?
The Z radios don’t get rebooted with a hub reboot, and a full power down is required to fully reboot them. This is usually the first thing I try if I have zigbee issues, which is fortunately very rare for me.
Another trick you can try is to swap the 2 hub antennas,
maybe the one for ZigBee got lose.
I would suggest to give [Zigbee Map ]
community app a try. It talks to every device in the zigbee mesh and draws a visual representation of the found "connections". Note: you would need to have the HPM (Hubitat Package Manager) community app already installed, in order to install Zigbee Map though
Also take a look here : [C8 - 2.3.9.154] ZIGBEE not responding - #38 by jsarcone