Jetpack infinite scroll not working on Twenty Twelve [closed]

I just updated Jetpack and the theme, and the infinite scroll doesn’t work anymore.

I have tracked the console, and the XHR does receive the content of the posts to add but somehow it isn’t displaying them.

My blog is: http://jorjon.com/blog/

I have no custom modification whatsoever.

Update: Thanks to Jared, I have found this Javascript console error:

Uncaught SyntaxError: Unexpected token < jquery.js:2
v.extend.parseJSON jquery.js:2
(anonymous function) infinity.js:208
l jquery.js:2
c.fireWith jquery.js:2
T jquery.js:2
r

Update 2: This is what is being returned by the XHR, supposedly there is an unexpected token there, but I can’t find anything. The JSON at the last line, as Jared mentioned, is Valid. http://pastebin.com/ZUD2xqun

Well, the response should be JSON only. Not some HTML with JSON at the end.

Seems like the WordPress SEO plugin installed uses output buffering to output the meta tags in the HTML header. Have you tried deactivating this plugin or others? Maybe you can deactivate output buffering in the plugin alltogether.