So I had another drive on electric motor but with additional heater turned off. Result was no cabin heating whatsoever. After several minutes I turned heater back on and within a minute, with fan on higher speed pointed at my face, temp set to 25 C, I felt the heat.
So yeah, "additional heater" in the menu is the only source of heat in the cabin in electric mode, apart from seats/steering wheel if your car has it.
This concludes my testing. It's working.
Maybe software in your car is different or something, or temp sensor, which makes your car to heat faster and more aggressively on 22 C setting than mine. I have to crank to 25 C first to get heat, but I can live with that.
