Unable to copy all items into the inbound delivery

What causes this issue?

The system was unable to copy all items when creating an inbound
delivery with a reference to a purchase order.

System Response

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

How to fix this error?

You can only create inbound deliveries for the following purchase order
items with a reference to the outbound delivery using message type SPED:
Purchase order items that have a "GI-Related GR" indicator
(goods-issue-related goods receipt)

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.