I want a plugin to add some data into an order with

$envios = array (
                 [0] => '990083935372'
                 [1] => 'correos'
                 [2] => 'something...correoschile_etiquetas/990083935372.pdf'
               );
update_post_meta( $order_id, 'tiene_envio',  $envios );

The data gets added correctly to DB but it is not showing up in Orders "Customs fields".

And also get it called correctly by:

get_post_meta( $order_id, 'tiene_envio', true );

How can I make it appear in Orders "Customs fields"?