[Zubersoft]

Geoff is correct - it sounds like you had performance mode enabled. To disable performance mode, tap the lock icon in the floating toolbar at the bottom right corner of the library screen. This same toggle can be accessed by tapping the bottom right corner of the screen while a song is loaded to display the quick action box. If performance mode was enabled, that would prevent you from accessing the song overlay. As a side note, if performance mode is on, you'll see a notification pop up when you first load the app letting you know this.

Mike