Spotify uses data when playing offline playlists

[PariPari]

Hello,

spotify - again - eats up my data plan when playing offline playlists. 

I recently got a new iphone and installed everything from scratch, so a reinstall wont help. I also resetted the "offline devices" list and its only listing my iphone there.

Still, spotify used nearly 150mb since 31.05.2017 doing nothing but playing offline playlists.

When will this be finally fixed? Its not the first time this has happened...

regards