3557846 - All Partner functions maintained in the BP are not getting populated in the partner data tab in purchase order

When creating a PO with reference PR, or create PO in Create Purchase Order - Advanced(ME21N), these Partners are missing.

• Although Partner Roles (PI, OA etc.) have been maintained in the Maintain Business Partner(vendor master), these same Partner Roles cannot be copied to PO when creating the PO with reference PR.
• Adding these Partners to the created PO afterwards and saving does not work either, these are blanked / reset.

SAP S/4HANA Cloud Public Edition

Partner function, VN, OA, PI, GS, purchase order, purchase requisition, business partner , KBA , MM-PUR-GF-PA-2CL , Partner (Public Cloud) , Problem