Smart radiator thermostat overrides main thermostat

I have my main thermostat in a corridor and a smart radiator thermostat in a living room.

If someone manually reduces the temperature of the radiator thermostat, it turns off the heating (combi boiler) completely , even if the corridor is colder than the main thermostat setting.

Have only spotted this in the morning when you find the heating hasn't come on

I'd have expected the radiator thermostat to just stop the water flow into the radiator its attached to?

How is Tado meant to work with multiple thermostats? Switch of the heating if both are at the correct temperature of if just one of them is?