HTC One won't store offline playlists on sd-card

[Slackware]

Hey, 

I have a HTC One M8 with Android 6.12.401.4 . 

I have tried everything possible, but Spotify wont load my Playlists onto my SD Card. 

I deleted cashe and everything, deinstalled the app, deleted com.spotify.music, enabled storage rights for spotify after redownloading, manually creating the folder on the SD card. 

Now i noticed with the new Android version, i can put Spotify as an app on the SD-card. Did so, but now it will show that it loads to the sd-card, but fills up my Internal storage so that it stops downloading after a certain time to tell me my storage is full. 

I really have no clue what i can do, i have many playlists, and now they just won't move to the SD-card 😞

I'm sitting here for hours trying everything, nothing worked. It shows that it stored the app itself onto my SD-card, yet it fills up my internal storage. 

Im close to giving up. 

Please help 🙂