// Class OrderHistory: changeIdOrderState() & Order current_state

classes/order/OrderHistory.php

@@ -217,6 +217,7 @@ class OrderHistoryCore extends ObjectModel
 			die(Tools::displayError('Invalid new order state'));
 
 		// the order is valid if and only if the invoice is available and the order is not cancelled
+		$order->->current_state = $this->id_order_state;
 		$order->valid = $new_os->logable;
 		$order->update();