Same problem, I posted a different thread but was directed here. Just for completeness here is my full post:
Each day I record a local radio program manually and then add it to iTunes to listen to at work the next day. When I add it to iTunes I fix up the Artist and Album info and then change the media type to Podcast. Prior to version 11 this worked great, the show would show up as a podcast, where it would be easy to find and I could see at a glance if I have listened to it or not (the little blue dot next to it). Now that I've updated to 11 this doesn't work. I can go through the same motions, however after choosing Media Kind = Podcast and clicking "OK", nothing happens. All the other info updates properly, album/artist, but it will not show up as a podcast. When I Get info on the song again it still shows the Media Kind = Music. It will not take the change.