local files

[Evanesce]

I've been trying to sync local files to my phone for days and have finally reached the point where they are no longer greyed out and have the green downloaded icon however when I play these songs via the phone the timeline scrolls through the correct length of the song but with no sound playing. I believe they are successfully downloaded on the phone because sometimes after a full reinstall the first local file song I play after downloading works and is audable however anything proceeding that is not. Official spotify songs play fine. The local files also play fine in the desktop app.

All that I can think is that spotify is disallowing read access to the file after they've downloaded for some reason and can't work out why.

android version: 8.0 (no root)