This issue has come up before last year in some other discussions, but after the latest update it seems to have returned. This is my first time experiencing it on my phone.
About a week after this current Spotify update 18.104.22.1684, I've been having issues accessing Spotify through my car's (2017 Elantra) Android Auto display. I can't access any of the Spotify menus or see the Now Playing screen. I can start the last played song through by turning on the stereo but I have no controls for it.
Other music apps such as Google Play Music work fine, so it is presumably Spotify's problem. The current workarounds don't work very long, one being disconnecting the bluetooth conenction to the car, since Android Auto automatically reconnects to it and breaks the Spotify app again. Maybe some sort of conflict between the Android Auto and bluetooth controllers, which hasn't been a problem before- it should defer to Android Auto through cable. Some say the handoff between WiFi and cellular data is also broken, which also was never a problem before. I don't even have cellular data and leave it off. Another solution was to enable all app permissions for Spotify. Which also doesn't work, and I would like to keep them disabled except for Storage. This also has never been an issue before. Clearing Spotify data and redownloading hundreds of songs is not an acceptable workaround. I've already done it twice. Some of these workarounds might work for you, but as users we should not have to do this at all.
I'd like to keep bluetooth enabled, since I wear an Android watch. Or preferably get this old issue finally fixed. Currently downgraded as a temporary fix.