Solution : https://service.sap.com/sap/support/notes/308245 (SAP Service marketplace login required)
Key words : 
additional key words hpos, sales order, shipping point, dialog box, product selection, free goods, vbap-vstel, program error, solution implement, attached correction
Related Notes : 
       
| 321021 | Unwanted redetermination of the route | 
| 214563 | Unreq.shipping point redeterminatn with SH change |