Why does the Threesixty only start heating again when the temperature drops?

This is due to the built-in thermostat with hysteresis. This feature prevents the heater from switching on and off too frequently around the set temperature.

For example, if you set the temperature to 22 °C, the Threesixty will stop heating once that temperature is reached. It will only start heating again once the room temperature has dropped sufficiently. This creates more comfort, less switching noise and more efficient energy use.