My truck is the same way this winter, winter number 3. When I remote start via key or app, the steering wheel is warm, the heat and fan are running, but the seat is cold as ice. As soon as I press the start button, the seat lights turn on and it starts warming up. I have had it set in auto since I got the truck and they would always be blowing air in the summer if over 95 outside and warm in the winter time.
I have not done any Forscan changes or taken the truck in for any updates, still have all three recall notices sitting on my desk. The only thing I can think of is that the truck's settings are at Auto for over the air Sync updates. Not sure if it ran one or not lately.
Erik