Mapping Set for Inventory Valuation is not Working

Hi Experts,

I am facing an issue in Cost Accounting, I have set my Inventory valuation costing by using a mapping set and I used "Costing Category Identifier" as a source and added all the possible categories in the mapping list and assigned relevant GL codes. When I ran the accounting system it picked up the correct valuation account from the mapping set I defined if the transaction comes from the direct source of the Purchase Order receipt but if the source of the transaction at PO differs as any update on item valuation comes from AP source then the system is