Could not find the exact reason, but this is the JS error I got.
Error comes from tinymce-3.js line 71, if I remove it, everything works fine.

Files: 

Comments

Sorry, SVN patch, apply with patch -p0 < file.patch

Status:Active» Postponed (maintainer needs more info)

The error would indicate JQuery is unable to find the field Wysiwyg is about to attach an editor to, or the value in it.
If that is the case, I'd think there should be more errors appearing all over the place. Is the editor working correctly and syncing changes back to the original textarea? Have you tried 7.x-2.2 or 7.x-2.x-dev?