That's a great observation.
Thank you for bringing this up and I am sure it will help a lot of other users as well as our product team to improvise the software.\
Same issue. Any resolution?
I've ran into the problem a few more times since this topic was opened and resolved. Everytime the problem was the fonts, more specifically a widget or something uses a font you either don't have installed on your computer or it's not working properly. If that's what it is then change the font to something you do have installed and it will export. At least it worked for me.
Make sure you use Muse with TypeKit supported fonts.
The issue I now have is getting TypeKit to work on S3 Amazon AWS standard service....thoughts?