Like many users here it seems, about once a week my Android Spotify app loses all of the albums I have marked for offline download. Sometimes it forgets entirely that they were ever downloaded and installed have to toggle offline back on for each one, other times they stay selected for offline play and it just has to download all the data again. This has been going on for a couple months.
Lately, though, I'm seeing an even bigger problem. Whenever it loses all my saved tracks and decides to redownload them, it often starts downloading over mobile data even though I have download on mobile data turned off (checked multiple times). This has resulted in over 2gb data used by Spotify over the last two months, mostly in large incidents like one day when it downloaded 600mb before I noticed what it was doing.
At this point data usage is starting to cost about as much as my Spotify plan and I'm likely to cancel. I've tried removing and reinstalling the app, clearing the apps local data and logging in again, etc. Any ideas?