Thanks for reaching out to us about this.
Just to confirm, by "turn the app off", do you mean that you exit the app but leave it on stadnby in the background, or do you close it completely?
In any case, do you mind trying a clean reinstall, making sure to clear all Spotify app data? This tends to solve a lot of common issues our users face.
If that doesn't work, get back to us with the exact version of Spotify your phone is running and we'll take a closer look 😉