Related meta disappears after wp_update_post()

First of all: thanks for the plugin.
Now the problem: calls to standard WP function wp_update_post() reset any related field content. I.e. the Simple Page Ordering plugin reset all related fields every time you re-order (with drag&drop) your pages!

I think the problem is method save() (lines 118-130 in current version). The condition:
if (!isset($_POST['related-posts']) || empty($_POST['related-posts'])) is always true if the update is a low level update, via wp_update_post(). The line above delete the meta.

Probably the code should delete the content destination only if the $_POST[‘related-post’] is set (and empty).

if(isset($_POST['related-posts'])){
				if (empty($_POST['related-posts'])) :
					delete_post_meta($id, 'related_posts');
				else :
					update_post_meta($id, 'related_posts', $_POST['related-posts']);
				endif;
			}

Ciao;
Matteo

https://wordpress.org/plugins/related/