So this is my schedule:

I drive to work while listening to Spotify from my iPhone over bluetooth in my pocket.

After a work day, where I also use my phone, when I want to drive home, Spotify only rarely resumes it's playback. I can't figure out a pattern for this, if it's because Spotify were not used for a while and iOS simply closes down the app or something like that.

But usually when I open Spotify to see why it is not playing, it just shows an empty list as if it has completely forgotten what it was playing previously. Then I have to go all the way back and choose my playlist again.

I can't reproduce this quickly. If I go down to my car, play some music, stop the car, mess around with my iPhone and then starts my car again, it works fine.