Have you reported this to the MuseFree support team?
I am sure they would be able to check out the issue.
Meanwhile, you can also share the file with me so I can test if it is a Muse issue or any wrong with the fie itself.
For sharing the file you can upload it to any file sharing service like Dropbox and send the link to me in a private message.
For doing a private message hover the mouse on my picture and click "message".
From the support said me, that tested the file on 2 computers and no problem.
In that case please share the file with me as mentioned above for further investigation.