Thanks for responding.
I just did several test videos, following the test steps you provided but could always export my video without any issue.
Even using the "Tables Have Turned" song, changing the title too it went well everytime.
So I'm thinking the issue lies elsewhere than the music. It's hard to be able to help if I can't reproduce the same issue on my end otherwise I would open a bug report for the Dev Team to fix.
Make sure to update the app to the latest version > 6.6