All downloaded tracks deleted.. again

[Axel456]

Dear developers,

It has been 2 years since I started using Spotify Premium and I will finally report a problem that has been annoying me too much now. 
I've used the app on my Oneplus One most of the time, and every month or so, I found my entire library (downloaded, playlists, albums..) to be unavailable offline (No green arrow indicating they have been downloaded for offline use). Every time this occured, my app information said the app still used 5 gigabytes of storage, so the track were still on my device somehow. Everytime I had to delete the app or remove it's contents and dowload the 5 gigabytes all over again to resolve this issue. 

Mostly I blamed the phone, but 3 weeks ago, i've bought the Oneplus 5t and the same issue has occured 3 times ever since on this device as well...

I know this problem occurs when your subscription to Premium ends, but this has never been the case, because I always buy a new prepaid card on time. 

Please can anyone suggest a sollution to this unbelievably annoying issue? It's very time consuming to download my entire library all over again and it's starting to drive me crazy.

Thanks

(specs: Oneplus 5t 128gb, android 7.1.1 with OxygenOS 4.7.4, app version 8.4.31.723 armV7)