Solution : https://service.sap.com/sap/support/notes/318616 (SAP Service marketplace login required)
Key words : 
additional key words basic date, newly calculated order start date, order start date remains, predefined order finish date, order start date, order finish date, -house production time, order start, order finish, basic dates
Related Notes : 
       
| 323609 | Basic dates are deleted or not determined | 
| 194019 | Basic dates, production start are incorrect |