Change Message for Unavailable Products in Native UI

You may want to change the display message for products that are either out-of-stock or are not available for Autoship processing ("Process Scheduled Order"). You can do this using the 'autoship_scheduled_order_item_stock_notice' filter (src > scheduled-orders.php). It takes parameters of the displayed message (html), $item, $scheduled_item, $autoship_order, $customer_id, $autoship_customer_id. You will only need the parameter for displayed message in this case if you are simply trying to change the display. 

Example

function change_native_unavailable_message($message){
	return sprintf( '<span class="autoship-item-notice"><i class="dashicons dashicons-warning"></i>%s</span>',  __( 'Currently Unavailable for Autoship', 'autoship' ) );
}
add_filter('autoship_scheduled_order_item_stock_notice', 'change_native_unavailable_message', 10, 1);

Before

After