Solution : https://service.sap.com/sap/support/notes/355692 (SAP Service marketplace login required)
Key words :
additional key words aleitem category alesva01me21, correct wrong purchase order items, respective sales order item, item category 'ales', purchase order item, correct delivery date, statistical delivery date, sales order, delivery date, = delivery date
Related Notes :
332509 | ME59 incorrect delivery date as of second PO item |
319682 | BAPI_PO_CREATE: PReq overwrites interface data |