Solution : https://service.sap.com/sap/support/notes/365571 (SAP Service marketplace login required)
Key words : 
additional key words ck11, attached program corrections, phantom assembly components, phantom assemblies, assembly scrap, cost estimate, costing result, component scrap, prerequisites note 112062, solution implement
Related Notes : 
       
| 485810 | Modific.: COMPUTE_FLOAT_ZERODIVIDE for material costing | 
| 377648 | Incorrect requiremt quantity after header change in quantity | 
| 112062 | CO01/02:Incor. phantm qties when changing headr qty |