Empty housenumber field

One of our clients has to be migrated to the latest version of PostNL. After this change all packages has been send as return to the store with the reason; invalid/unknown address. When we check these orders all shipping data is correct! As we look further we see a PostNL added field for housnumber that is empty. Is this the cause of the returning deliveries? Why is this field even there as Woocommerce has his own fields. Just read the housenumber and addition from the billing or shipping address_1 with fallback on address_2. Please fix this!