Have you tried disabling add-ons to see if they appear? If its not working on a default style with an unedited profile_post, there may be an add-on that is changing the output and accidentally removing the posts.
You have since disabled the add-on, which removed the template helper, to return the proper string. I have reverted the template change (in message_simple) to not have the template edit required by that add-on. You have two courses of action here:
Revert the other template edits (as defined in the readme.txt)
Revert the template edit I made (redo the message_simple template edit) and re-enable this add-on.