Music will not continuously play when IPhone is locked.

[ddonovan114]

I have Spotify Premium and on both my iPad and iPhone music will not play continuously if the device is locked. I have restarted the devices, reinstalled Spotify on both, and played around with the playback settings such as "Crossfade" and "Gapless Playback" and nothing seems to work. I hope someone can help me as I pay monthly and this is extremely frustrating.