Creating a scene for heating a room

I share your frustration.
It is generally considered better to place the temperature sensor outside of the radiant area of the panel, as this will provide a less than accurate measure of the air temperature in the room. As I said before I do not controll with temp sensors, as I see little benefit with IR, air temperature is far less of a consideration, but you may find the best way to do it is via a hard wired thermostat. I would also say that many smaller panels, distributed across the ceiling deliver a better solution than one large one such as this. I hope that helps.

As I understand it, this is because the ambient temperature did not change from “unmet” to “met” between the defined time periods A-B, so the scene did not take effect.

If you want to dexecut this once when entering time period A-B, you can add a scene:
IF (All condition is met)
Time point A;
Ambient temperature ≤ X
THEN
Doing sth like heatting…

In this way, the scenario determines and executes once at time point A, hope it can help.