Why can suppliers send an ASN containing items that have not been previously confirmed?

Why can suppliers send an ASN containing items that have not been previously confirmed, and the order has a partially confirmed status?

This behavior occurs regardless of whether the rule "Require suppliers to create an order confirmation before creating a ship notice" is activated.

See the example below:

- PO: Line items 10,20,30

- PO: Supplier confirms item 10. Then the button "Create Ship Notice" is activated.

- ASN: The supplier creates a ship notice for line items 10,20,30.

- The status of the order changes from "Partially Confirmed "to "Shipped".

This ASN is received in SAP without previous OC of Line item 20 and 30