Episode shows up in Podcast app but is "not downloadable"

I am aware that iTunes is having some problems but I can't tell if this is associated with those since I had this same problem once back in November and it was never resolved.

I podcast on Tumblr, but I use feedburner to create enclosures on rich media entries labeled #podcast. I also make sure that the first link on the entry is a link to the mp3. This has always worked in the past, with the exception of my second podcast post on November 20th, which showed up in the Podcast app but not on iTunes. In the Podcast app, it had an image of a file on it and when clicked, a message appeared stating that it is not downloadable. Eventually, the file stopped showing up.

My most recent episode was posted this morning and this same thing happened; it didn't appear in iTunes and in the Podcast app it had the same file clipart and message saying it is not downloadable. I deleted it and reposted it twice, the same thing happening both times. The latest attemp can be seen in my feedburner, where all looks well.

Can someone give me some insight as to what the problem might be? Will it work itself out or will it never reappear in iTunes like my November 20th post? Any help you can offer would be grately appreciated.

My feedburner is: http://feeds.feedburner.com/HotChristmess

My podcast in the iTunes store is: https://itunes.apple.com/us/podcast/hot-christmess/id581372446?mt=2

My Tumblr is: hotchristmess.com

Thank you!