Spotify not able to resume playing offline playlist without network connection

[AeroZ]

I got a playlist downloaded for offline play.

When I stop playing the offline playlist, close Spotify from the app switcher, switch my iphone to airplane mode and re-open Spotify then I'm not able to continue to play the playlist that I paused earlier. At the bottom of the app I just see "Spotify is offline." If I disable airplane mode then my previously played song pops up from the bottom of Spotify app and I'm able to resume the playlist.

Why does Spotify need network connection to resume a playlist that's downloaded for offline play?