Similar problem
I'm getting the exact same problem, the file seems to upload OK as the progress % increases but on completion I get the message: "Error uploading file: No File Uploaded"
This is an issue with the new HTML Editor file handling within Power CMS 2.1.1 and not an issue with file upload in universal-email there is no "All Uploads" tab so I can't look at any debug information.
My files are very small and worked fine in the old CMS 2 HTML editor file handling. This is not a permissions issue.