Can't download music on Premium

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I have Spotify Premium on my Galaxy S7. I download my music because I often don't have signal/wifi. 

It's happened twice that most of my music gets "undownloaded," which is really frustrating, but a few days ago all of my music suddenly undownloaded. What's more, when I flip the switch to download the music (which had fixed the problem previously), nothing happens, and when I leave that screen and go back, the Download switch is back to its off setting. A lot of songs also don't have the option to "save" next to them (as if they were downloaded) but when I don't have signal or when I go to offline mode, they're not available.

Any ideas? I checked my account and my payment is current. I uninstalled and reinstalled the app. This is really frustrating and I'm seriously considering switching to Tidal since this has happened 3 times already.