In meta-box-aio/meta-box-aio.php you start the session before other plugins are loaded. That prevents https://wordpress.org/plugins/wp-session-manager/ to work.
As per comment, maybe make sure that “MB Frontend Submission & MB User Profile” are enabled before starting the session? We don’t use it on our site for example, but we use the session manager.
You must be logged in to reply to this topic.