Best answer by Gina
Thanks for posting to the help forum. When you go to http://soundcloud.com/settings/extra, you will have the option to check or uncheck the box at the top of the page that says "Enable podcasting for all my tracks by default." If the box is checked, all new uploads will be added to your RSS feed. For now, can you go into your missing episode's settings and enable the 'Include in RSS feed' option. It can be found under the permissions tab in the track edit page.
Hope this is all clear!