I think there is an undocumented feature in the software (which I find very useful) that switches the pump off if the pillefyr is working and boiler temperature is less than pump start temp - 12K (not sure about the 12K, I think it's between 10K and 15K). In other words, when the boiler has trouble maintaining the target temperature (e.g., because DHW was just started), the pump gets switched off so the boiler does not "cool out".
That's not going to work with a start temperature as low as 30°.