Not sure if it's a Spotify issue or an iOS issue but here goes, hopefully someone else has seen it.

I have automatic update downloads enabled in the appstore so never notice when Spotify receives an update; I also have Mobile data switched off for spotify in the iOS settings as it's an easier way of toggling Offline mode when I'm not on WiFi.

The issue is that when Spotify is updated, this setting is ignored by the app (the iOS toggle stays off) so Spotify starts using data until I flip the toggle on then off again.

This can be a real pain if I don't check to see if the tracks playing aren't in my offline library, seeing as I have my quality set to extreme.