Cannot add agreement at PO line when supplier site differs from agreement site

We are encountering a scenario where a requisition is created without a source agreement and is subsequently converted into a purchase order.

At the PO level, the buyer creates a change order and attempts to apply an agreement (CPA) at the line level. However, if the supplier site on the requisition/PO differs from the purchasing site defined on the agreement, the agreement does not appear in the search results and cannot be selected.

When the supplier site is changed to match the purchasing site on the agreement, the agreement becomes visible and can be applied.

At the same time, based on the 25B feature “Purchase from supplier sites not assigned to a procurement contract”, the system allows requisitions to be created using an agreement while selecting a supplier site that is not explicitly defined as a purchasing site on the agreement.