I also had this problem suddenly today. List of 2600 songs and lots of playlists displayed OK, but selecting a song just gave me a black screen with the play controls. The song would play but not displayed. The problem was solved (I hope...?) by double-clicking the Home button, removing iReal from memory, turning iPad off, then restart. I have used iReal on my iPad2 for nearly half a year, this has never happened before.

iPad2, iOS 7.04 (11B554a)
iReal Pro 5.0.2 (17130)

kind regards,