[Plugin: Post Type Switcher] Switch to Custom Type Not Being Saved

I’m having exactly the same problem. I think that it worked fine up until 3.1, this is the first time I’m using it past the upgrade.

I can suggest a temporary solution of this issue.

Add the following code to the end of
wp-content/plugins/post-type-switcher/post-type-switcher.php
file. Just before php closing tag (?>).

function pts_save( $post_id, $post ) {
	if ( isset( $_POST[ 'pts_post_type' ] ) && $_POST[ 'pts_post_type' ] != $post->post_type ) {
		$cur_post_id = $post_id;
		//checking if current post is a revision
		if ( false !== ( $id = wp_is_post_revision( $post ) ) ) {
			$cur_post_id = $id;
		}
		//updating post type
		set_post_type( $cur_post_id, $_POST[ 'pts_post_type' ] );
	}
}

add_action( 'save_post', 'pts_save', 10, 2 );