Music track cuts off

No matter what I do, the last three seconds of the music track at the end of a five minute project cuts out. I've switched sound tracks, moved the library to another computer but it's not working. I send the project out via Share master file, Send to Compressor -- it makes no difference. Any suggestions?

And of course, I'm on deadline.

Computers: started project on a loaded 2012 Retina MacBook Pro (OS 10.11.5) FXPX 10.2.3, moved to 2013 Mac Pro (same OS and FCPX versions)

Thanks,

Tom

Apologies to all; I came up with a solution, though I'm clueless why it works: Copied and pasted everything in the problem project into a new blank project. Music fades out as it should. Go figure.