I have custom post types and custom statuses registered. The post status is updated from a custom drop down box that I have inserted into a metabox on the edit post screen.
It works fine, however whenever I update a post or create a new post and set the custom post status from the dropdown, it resets back to "Published".
It seems that if either the Publish button is pressed when creating a post, or the Update button is pressed when editing the post status always defaults to published.
PS: I used the codes from here: New post status for custom post type