ST Nest Thermostat unit of measure

Hi all,
New to here so apology if missed answer to my problem.
I’ve got ST & Nest thermostat integration going on. Back in the day it was connected via webcore but when direct integration was offered I took the hit.
Initially things were working ok but now have an issue where within ST the unit of measure keeps on jumping between Celsius and Fahrenheit for no apparent reason.
This as a result upsets all sort of automations as for example ST has Nest as Celsius, the automation state to set temp as 18C. Then ST switches Nest to Fahrenheit suddenly the automation updates itself to be 18F which is below minimum value for Fahrenheit thus stopping automation from working.
Opposite apply when I update rule to work with F and ST changes to C.
Does anyone have same issue and or does anyone know of permanent fix?

I would also be interested to know if there is a solution to this as mine does the same.