Are you getting heat when the engine is operating? Also, in your drivers screen on the power usage page, are you seeing 3-6kW at "idle"? If you see anything above .5-1kW then your heater module is likely still working ok. There have been many heater issues with the Gen 1 ('13 in particular) which is fixed with a firmware update however there are also other simple items that may be at fault. One of those items includes a 3-way valve that separates the heater circuit from the rest of the coolant loop through the engine for EV mode. If this valve is stuck for ICE heater operation, it may not be circulating the hot water from the K10 heater (EV mode) to your heater core.
I would definitely try at least running in hold for several minutes to see if you get heat with the engine up to temp. If you do, it may be the 3-way valve stuck. I recently had to have mine replaced which was stuck in "EV" operation and blew ice cold when running the engine. It also apparently plugged some sort of inline filter. Cost for repair would have been about $300 but I had a GMPP that covered it.
