Volume cuts out on a recorded track.

Garageband Mac - My Song was fully recorded and all tracks working perfectly, however all of a sudden the volume cuts out a certain points of the vocals and other instrument tracks get quiet or cut out as well. I have rebooted to find the same issue. The volume cutouts are at the same point every time track is played. Oddly the visual display of vocals and music looks intact as if they should play correctly. The only thing I can thiink of is that the song was left open over night. Could the tracks have become corrupt without doing anything and wouldn't that show up on the display as well? or is something else going on?

Lost on this and how to fix, Thanks.