Odd opentherm behaviours.

I've just wired my extension kit up to my WB greenstar classic as per the tado instal document and it seemed to make it cycle quite a bit today while I was keeping an eye on how it was working. Temps were set to 18 in the house so I turned them all up to 19/20 to make the boiler work a bit harder as it had been suggested it had modulated down as low as it could.

At times now I notice that even if I turn say the living room up to 25 and the temp is only around 20, the boiler won't fire to bring the room up to temp, or it'll fire for a time then switch off but switch off before the room is up to temp.

Just looking for some pointers on what it could be before I contact support for them to check it out.