Audio portion of project missing when shared

I'm suddenly having problems with the video file's audio not being included in the final versions of my project when shared to both Windows and YouTube. The music track is included in all cases, but not the audio associated with the video itself. The first time this happened, I was able to exit the project, open another project, then return to my original project. Then when I exported the project to both Windows and YouTube., all of the audio was included. Success! The next time I shared a project though, the same error occurred, even after I closed Rush and re-opened it. I'd like a solution that doesn't require funky workarounds. Please advise. Thanks.

Paul Hvidding