Premium User -- Offline Downloaded Songs Disappear When Disconnected from WiFi

[vanovekn]

I hope you guys can help me out. This issue has happened on and off for the past year or so since becoming a premium user.

A few times over the past year, I've noticed all of the songs in my Spotify library have vanished from my device, and need to either be downloaded again, or they don't even show up in the grey until reconnected to WiFi. The problem only seems to occur when not on a WiFi network.

I saw this has been an issue for some Andriod users, and wondering if anyone has noticed this on iPhone? I thought it was a user error, but after the lastest incident yesterday, I know it wasn't anything I did. 

I have an iPhone SE. The Spotify app is up-to-date. My Macbook Pro library is not impacted. 

Please help! I can't imagine if this happened when leaving for a roadtrip, air travel, or commute into work.