Sheet Music not playing

Every time I leave the app for even a minute, I come back, and I cannot seem to play the music. I have to close the app and restart it in order for it to play. All it does when I press the play button is leave a blue line in the beginning of the notes which is supposed to move along with the music, and it doesn't move. Nothing on the actual app seems to help it. I googled it and some people seem to have the same problem. I have already got the latest version updated as well. What is the issue?