I am also having this problem.
I’m using Rackspace Cloud Files, and have successfully exported everything except my media library.
When I try to export my media library the process only takes 19 seconds, the progress bar ticks up and finishes at 101%, reporting that 900 of 891 files have been uploaded, however, looking at my container on Rackspace, the files have definitely not been uploaded.
I have installed Fileinfo and phpinfo() confirms this.
Frederick I have submitted a bug report via the Support tab.