I manage a church website (http://www.oslc.org.uk) and use the blog post function to publish recordings of sermons. The feed is published on iTunes and elsewhere as a podcast.
To save server space, I recently stopped uploading the recordings onto the server, linking to a public folder on Dropbox instead. Since then, the podcast feed (http://www.oslc.org.uk/feed/podcast) is no longer updating: WordPress is not creating any enclosures.
I have searched the forums and spent a considerable length of time trawling Google for a solution, but haven't found any help at all.