Query WooCommerce orders where meta data does not exist

I’m trying to fetch all my WooCommerce orders where some additional metadata is not empty. $orders = wc_get_orders( array( ‘orderby’ => ‘date’, ‘order’ => ‘DESC’, ‘meta_query’ => array( array( ‘key’ => ‘var_rate’, ‘compare’ => ‘NOT EXISTS’, ) ) )); So if the ‘var_rate’ is empty or doesn’t exist then do not return that record. At the moment all orders are returned using those arguments.