Help with Hive temp readings

Hi all.
I have a strange problem and I can’t work out what’s causing it.
I have a Hive thermostat (SLT3b) and Hive receiver connected to my Combi boiler (SLR1 only recently supported)
I have them both paired to Zigbee2mqtt and paired to each other.
And mostly everything is working fine it’s turning the heating on and off etc.
But my problem is when I load up the Zigbee2mqtt dashboard and watch the local_temperature it fluctuates,
so roughly every 1-2 minutes the temp reading will jump up by random amounts roughly 1- 1.5° and then drop back and its repeating this all the time.
But the reading on the Hive thermostats display isn’t changing as that remains the actual room temp.
I’ve tried deleting and repairing them both and I’ve updated everything to the latest version like HassOS and the Z2M add on and nothing showing in the logs, I’ve also moved the thermostat closer to the receiver and also closer to the ZigBee dongle but neither helped.
So I’ve ran out of ideas now and hoping someone’s heard of this before.