Solution : https://service.sap.com/sap/support/notes/660114 (SAP Service marketplace login required)
Key words : 
parameter id gcf prior, activate parameter gcf, extras --> definitions --> change, generated objects represent, report writer functions, generated objects, report writer, activate setting, object generated, report group
Related Notes : 
       
| 388485 | Flexible analysis: Inconsistent control table entries | 
| 174132 | Flexible analysis: Composite note | 
| 65301 | Flex. analysis: Enhancements with Report Writer techniques |