Spotify Version - 6.8.0.3786

Device - Apple iPod Touch 6th Generation

After a while of playing through several songs, Spotify will just randomly stop in the middle of a track (all tracks are downloaded). The app itself is still responsive and doesn't crash, however the track will just stop playing and the progress bar will just freeze. The app definitely isn't going into pause mode when this happens, as the play symbol doesn't appear, and the pause symbol remains on screen the whole time. Sliding along the progress bar or skipping to the next track will get it working again. However, going back to that track and trying to get it to play from where it stopped doesn't work; it just stops. This fault is affecting several tracks in my library.

De-selecting the 'Download' option, then re-selecting it again seems to fix the problematic tracks. But the problem keeps happening on other tracks. 

I've re-started the app, I've re-started the device, I've deleted and re-installed the whole app; nothing has fixed the problem. Thinking the next step is a factory reset?