Thanks for pointing this out. I'm amazed I haven't run into the problem before. It turns out my subscribe function started by decoding the URL so the + or %20 encoding was stripped out by the time it was fetched for parsing. I added a step to change spaces to + and was able to successfully subscribe the feed you mentioned.

That feed also had the side effect of exposing another bug since all of the items have the same title. I typically mark items as duplicates within a feed if they have the same title and are within two days of each other, but there was one spot in the code that didn't check for the date.

Thanks again.