Snapshot Pro failing to produce an importable ZIP file

When I run Snapshot Pro it produces an archive file that is invalid. When I try to import it (on this site or another) I receive the error message "manifest data not found in archive". I see something similar reported on the forums but none of the reported solutions are working for us.

I could send you a copy of the ZIP to examine but it is 70MB in size and contains some confidential data. I have the WPMU DEV dashboard installed. Please advise on the next step.