Downloaded music undownloads whenever I close the app

[Gogetsome]

Hi,

     I'm on the Galaxy S5 and whevnever I open Spotify It's always downloading 30 to 100 songs, even after I've downloaded them. It's been happening for about 2 to 3 weeks ever since I downloaded 2 new albums, and I've deleted those albums to see if thats the problem but it wasn't. A couple days ago it undownloaded all of my music so I had to redownload all of them again. I've uninstalled the app and reinstalled it with no luck. A few playlists (mainly the two with the new albums) are always waiting to be downloaded, but now its starting to happen with other playlists. Instead of the green arrow they have the grey arrow until theyre downloaded, but once theyre downloaded and I close the app or lose internet connection they undownload. For example when im driving and listineng to music all of a sudden it will stop and I'll check it and they wont be downloaded.  

If anyone has a fix for this that could help that would be awesome.

Thank you