Dear KP
This is standard behavior of SAP, if you cost your FG or SFG material through CK40N it costs all the materials inside the BOM even if they are having price control V such as RMs or any other bought out materials, and update Standard costs to them even. But This standard costs is statistical only and will not be used in Standard cost of FG or SFGs unless you have specified in your valuation variant.
To avoid materials having price control V during costing run:
In valuation variant you should maintain 'Valuation price according to price control in material master' as first strategy for material valuation.
AND/OR Tick 'DO NOT COST' indicator at costing 1 tab of material master having price control V.
Regards
Rajneesh Saxena