I have and the lowest lastHopLqi is 238 so that is all OK.
lastHopRssi figures are between -44 and -77 which I think all is OK with this too.
I've checked that as well and there are no anomalies there either. The removed zigbee device is not showing.
The devices that the strip replaced was a z-wave and a zigbee device and these have both been removed from the hub as well.
I just cannot find what is causing it and it all started around the time of the devices I mentioned inclusion.
I have just repaired all the devices in one room on to my old C3. When/if this issue arises again I will be able to see if it hub related or device related.
Thanks for the input though.
I'm starting to divert this thread so I may take it to a new thread if things continue.
Sorry to bother you but did you manage to connect the contact sensor to Hubitat? It doesn't work for me. The device is discovered as "Device" and changing the driver to Generic Zigbee Contact Sensor didn't do anything.
Update: after another factory reset it works. It might be that this time I added the sensor through type (both times) and not letting it decide what it was.
Thanks everyone who helped along.