Since the the most recent update of iTunes we have seen a bug occurring with some user’s Plus+ feeds. Please note that if you are on the “My Podcasts” view you will not see the error below, you will how ever notice that your podcast feed will not automatically update on occasion. It is the same issue, the error only appears in the “List” view.
If you keep seeing an exclamation point next to your Plus+ feed and the error below please log into your Dashboard for detailed instructions on how to edit your feed to avoid this issue.
Once you have done the fix found on your dashboard, click the refresh icon above your feeds multiple times until it populates.
We are currently investigating what is causing this but as of now believe it is simply a bug with how the new version of iTunes handles authenticated podcast feeds.