All my downloads disappeared

[abenn1]

I have Spotify premium and had dozens of albums downloaded to my phone. I was in the middle of listening to one downloaded album on the subway -- possibly with an intermittent network connection -- when it stopped playing. When I looked at my phone, all my music had disappeared from my library, whether downloaded or not. All albums, all playlists -- everything. Now that I am back above ground and have an internet connection, my library is back but none of my albums are downloaded any more.

What the hell happened to my music? I've lost a lot of trust that Spotify's downloaded music will be there when I need it. What do I do when this happens at the beginning of a five hour flight?