p2 publishing authorization

Hi!

I am having a small issue with P2 WordPress theme. As of now, contributors can publish posts from the frontent. When I access the Edit posts panel after that, I get the following error mesage on the top of the post list column: it signs the post as Mine:
Warning: Illegal offset type in isset or empty in /opt/WORDPRESS/wordpress/wp-includes/post.php on line 725

Ideally, I would like that post to have the status “Pending”. Is that possible? If yes, how?

Thanks for your help!