Update orderline meta (qty)

Hi,

I am trying to add meta-data to my orderline items.
But it looks like the “$quantity” output is not right, it is not taking the qty from the right product line?
Also what I actually want is that this meta data is being updated when an order is updated, not only when it is set to processsing.

Do you have any idea what I am doing wrong?

function add_pakket_aantal_productline( $items, $order ) {
	foreach ( $order->get_items() as $item_id => $item ) {
	  $quantity = $item->get_quantity();
	  $product_id = $item->get_product_id();
	  $product = wc_get_product($product_id);
	  $step_value = $product->get_meta('_alg_wc_pq_step');
		  
	  $pakket_aantal = $quantity / $step_value;

		$items = $order->get_items();
			foreach ( $items as $item ) {
			  $item->update_meta_data( '_pakketten', $pakket_aantal );
			  $item->save_meta_data();
			}
	}
}

add_action( 'woocommerce_order_status_processing', 'add_pakket_aantal_productline', 10, 2 );

Best regards,
Olga