Most recent Podcasts not posting on iTunes U

My last two podcasts aren't posting on iTunes U, though they are downloading to my subscriber iTunes account. However there is a white ! in a black circle to the left of my podcast containing the following message: CSDE Out Loud does not seem to be a valid Podcast URL.

I have no idea why I'm getting this message. I've double-checked my code against the iTunes sample code and successfully submitting it to the feed Validator.

My feed URL is:

http://csde.washington.edu/podcasts/csde_out_loud_d1.rss

My iTunes U URL is

https://itunes.apple.com/us/itunes-u/csde-out-loud/id431503316

Any help/suggestions is most appreciated.

fyi - this is the first time I've posed a question to this forum.