baxi ecoblue

We have a Baxi Ecoblue plus 24 combi boiler with the Baxi Ecoblue wireless thermostat (7212344) We have installed the nest 3rd gen thermostat. The boiler terminal blocks b1 and bk2 are connected to terminals 2 and 3 on the heat link. We have gone through the set up and all seems ok, there is a...