Solution : https://service.sap.com/sap/support/notes/194115 (SAP Service marketplace login required)
Key words : 
afvgd structure  afvgd optionalimplement, symptom operation dates, additional key words, function module 'cx_opr_fill_from_cxzeit', work start, transaction se37, import parameter, program correction, correction instructions, prerequisites
Related Notes : 
       
| 516490 | Latest finish 00:00:00 instead of 24:00:00 hrs | 
| 328307 | Start/finish date is on work finish/start | 
| 310919 | Incorrect dates at date limit | 
| 140896 | Incorrect calendar for scheduling elements |