Hi,
I had the same problem and did a quick fix for this version
In wp-content/plugins/simple-custom-post-order/simple-custom-post-order.php l.303 and 332, I switched the $where lines with
$where = preg_replace("/p\.post_date [><] '.+?'/", 'p.menu_order < ' . $current_menu_order, $where);
It replace the date test with the menu order one.
Hope that helps!
