Solution : https://service.sap.com/sap/support/notes/991599 (SAP Service marketplace login required)
Key words : 
create separate transport packages, sap enterprise portal, deploying portal content, imported content visible, complete folder hierarchy, imported folder objects, transport packages, imported content, complete hierarchy, folder objects
Related Notes : 
       
| 1033016 | Central Note - Patch 2 for NW04 Portal SP18 | 
| 1033015 | Central Note - Patch 1 for NW04 Portal SP17 | 
| 972506 | Known issues with Portal Platform SP18 | 
| 969413 | SAP NetWeaver Portal Platform NW7.0, SPS09 | 
| 968791 | NW04: Central Note for Portal SP19 | 
| 950400 | SAP NetWeaver Portal Platform NW7.0, SPS08 | 
| 946470 | Known issues with Portal Platform SP17 |