I have the same issue but lately I'm thinking its not really an issue, more of a bug.
When I turn on the climate from the app, it indicates both front seats and steering wheel are on full. But when I finally get in the car, the seats are not warm and the steering wheel is only lukewarm like its warm only because the dashboard blower is blowing hot air on it. I dont think they're really turning on.
And then there's this posting
I've noticed lately that my Telsla app on my iPhone will not control the seat heaters. Here's the scenario : I use the app to warm up the car and also the front seats. As of late - when I set the inside temperature, the front seats appear to be on Auto (high default.) When I tap the seat icons...
teslamotorsclub.com
Before all this, I discovered you can turn on the heater only by tapping the image of the car in the small space between the steering wheel and the side door, right on the dashboard. And by turning on heat only I mean only the blowers and defrosters are shown as being activated, not the steering and front seats. However, this seems to have disappeared with the last software update. Now the app shows everything being turned on no matter where you tap.