I’d be happy to take a peek if you still need help (with the permalink issue, if not the feature images) – unfortunately I can’t actually view your code, I just see a basically empty page. If you still need help can I ask you to post a new link to your code – perhaps via a different service like Pastebin or Gist?
How strange, it works for me (testing in an otherwise “plain vanilla” environment with just our plugins and the Twenty Thirteen theme) and does so whether I use your snippet above or below the theme’s own main loop.
Is it possible your theme or a plugin you are using might actually be conflicting somehow, perhaps by filtering on the post_link hook or something of that order?