webdav upload never completes in nautilus

I'm attempting to upload files via the webdav over ssl functions provided by Gnome.
Each time I attempt to upload a file, the copy dialog box opens (window title is "Copying files"), the progress bar reads "copying file 1 of 1", but never progresses.
Nautilus is not hung at this point - if I return to the window, I can navigate and even download files successfully. The copying files window never finishes; clicks to "Cancel" and the X to close the window are ignored.

Looking at the webdav server's web logs, it appears the PROPFIND to test if the file exists succeeds (returns 404 for a new file); the subsequent PUT request however receives a 401 (unauthorized). I have selected "remember my password until I logout" when connecting to the remote server.

I'm wondering possibly if:
- the session cookie is not being properly sent along with the PUT request
- something isn't properly handling the 401 response code?

My client is a vanilla ubuntu gutsy. The server is not apache mod_dav - it is a commercial product (I do believe the server is functioning properly though).