Offline files disappearing after app restart

[borgja]

I have recently bought a HTC One M9, and switched my SD card from my previous HTC One M8.

After downloading the latest version of the Spotify app, i startet syncing all my music down to my phone. 
First of all, it took a really long time, even though I have a really good broadband subscription (100/10). 3000 songs tok at least 5 hours to sync.

When I start the app again, all my synced music is GONE and I have to start the process all over again. 

Another 5 hours to sync all the files, just to experience that again, the files won't stick.

Tried to uninstall the app, format SD-card, completely remove cache before deinstalling, then reformatting the SD-card, another 5 hours of resyncing. But to no avail, the files simply won't stick.

It was not until I downloaded an older version of the app (ver. 2.8.0.1081) that I was finally able to make it work. Until Play Store automatically updated the app to the latest version, and all my files disappeared once again!

I have now installed the old app once more, and deactivated automatic updates for Spotify. 

In case you were wondering, to sync all my files to the phone, I also use an older version of the desktop programme, version 0.9.15.27.g87efe634

This version has the "Devices"-feature, which is removed in the last version of Spotify. I have also prevented it from auto-updating.

Is this a known problem?

[borgja]

This morning my phone started redownloading all my files AGAIN!

And the app is NOT updated to the last version..

Starting to get really fed up of this problem, anyone else or is it just me?

[borgja]

Yesterday I did a factory reset out of sheer frustration, and downloaded my playlists once more (via an older desktop Spotify with the "devices" - feature.
This morning, all my playlists started resyncing again!!

Uninstaller Spotify, installed, tried to log in, got the "no SD card found" error, formatted my SD, cleared cache, and logged in again.
Have now started to download select playlists, via the app instead and I hope THIS TIME it will work.. Fingers crossed..

[borgja]

Good and bad news:
Good news: The files stays downloaded!

Bad news: Files are syncing to phone memory instead of SD-card.

Can all of this be a problem with my SD-Card? It's a Sandisk Ultra 64GB U1 card

[borgja · Accepted solution]

SOLVED!
Finally I got it working.
Seems to be an issue with the old desktop application, song synced via desktop doesn't stick. Maybe that's why Spotify removed it?
Anyhow, after removing Spotify app, formatting my SD, making sure no residual files linger in the system, reinstalling Spotify, and marked every single Playlist as Offline, the songs finally stick to the memory card..

Hope my experiences can help others with the same problem 🙂