Solution : https://service.sap.com/sap/support/notes/1434835 (SAP Service marketplace login required)
Key words : 
document splitting generates individually split posting items, support package status sapkh50021, wrong posting key, prerequisites document splitting, special purpose ledgers, software component sap_appl, affected data lines, general ledger reason, general ledger view, document splitting
Related Notes : 
       
| 1484185 | Document splitting: Incorrect posting key in New G/L | 
| 1383862 | Document splitting: Incorrect posting key in New G/L | 
| 1340947 | NewGL: Posting key with clearing documents incorrect | 
| 1275613 | Unjustified error message GLT0 003 | 
| 1170400 | Document splitting: Incorrect posting key in new G/L & SL | 
| 1167546 | Dump TABLE_INVALID_INDEX in SAPLGLT0 | 
| 1041694 | Online-Split:Documents with incorrect debit/credit indicator |