App downloading over mobile when "Download using cellular" is off.

[frap_gadz]

I have an issue with the Spotify app for android whereby the songs in my offline playlists are being synced using mobile data despite the "Download using cellular" option being off.

What I believe is happening is that the app begins the download over wifi and if I then leave wifi range the download continues, but now it is doing so on mobile data. I have been using the app for about 9 months on this device and this is new behavior as of this month.