RSS feed no longer updates to latests posts since 3.5 update

Ever since I’ve updated to WordPress 3.5 I have noticed my RSS feed is not being updated. I also have a phone app that uses the feed and while on the live site we can see the new posts, the RSS feed and anything related to the RSS feed remains stuck on a posting that was posted over a month ago. Is there anyway to fix this issue? I’m now on 3.5.1 and it’s the same issue, RSS is NOT updating!