Having a conflict with Post2Post plug-in too. Associated posts won't display on the live site (admittedly this could be a theme issue), but in the admin the associated posts aren't displayed - it shows that there aren't any. When trying to "reconnect" the association, the plugin says I cannot make duplicate associations.
And, after connecting posts and publishing them, the association isn't displayed when returning to the post to edit.
Post2Post recognizes the connected post, it's just not displaying it in the admin. Nor are the connections being displayed on the live site, though as I said, this could be theme related, but I suspect it's not.