So I have a ZTE phone. When I listen to Spotify while I'm still on the app it works like it's supposed to. When I go out of it and open Instagram or Pinterest cause I want to listen to music and look at posts at the same time, it will stop working after maybe 2-6 min of being directly out of the Spotify app. It should still play in the background but that is not the case. I'm not sure if I'm doing something wrong. Please help.