I figured this one out. I need to add this to both "from" and "to" in the relationship:
'query_args' => array('post_status'=>'any')
I think this is a design flaw of how the plugin works. In the back end it should show the relationship even if the corresponding post is in draft, pending review or in private, otherwise results will be unpredictable upon publishing.
Following a revised logic, the listing of related objects in the back end should list all related objects along with:
- the post title,
- its status and
- a link to go view the related post
- a link to edit the post