I am probably wrong here, but I think there might be an issue with your documentation on the Post Object field found here: http://www.advancedcustomfields.com/resources/post-object/
My issue is with this section of code under Single Template Usage:
if( $post_object ):
// override $post
$post = $post_object;
setup_postdata( $post );
?>
Do we not need to first reference global $post before running setup_postdata? I was having issues displaying the data in one of my templates until I passed the reference to global $post.
Did I miss something?