Thermostat turns off shelly, but wouldn't turn it back on

Hey all,

I use Better Thermostat to turn my gas boiler on or off (by switching shelly behind it on/off)

My problem is that while it switches shelly off once the target temperature reached, but it wouldn’t turn it back on, once the temperature falls below target temperature, as seen on attached video.

Any ideas what could be the cause of this issue?