Persistent feed items

Sorry if I missed any discussion on this elsewhere in the forum!

Every now and again I get a feed item that won't go away. It's deleted, it's struck-through, but it never leaves the list. Occasionally I can get one to disappear, but then it comes back. Is this a NewsFox issue, or more to do with something originating with the feed source itself? Is there a way to purge this kind of persistent entry?

Thanks in advance