Solution : https://service.sap.com/sap/support/notes/321522 (SAP Service marketplace login required)
Key words : 
additional key words hr planning data, synchronize hr personnel master data, set field hrp1001-reasn, symptom message type hrmd_a, hr planning data, hrmd_a message type, yy = additional data, hr master data, database tables paxxxx, xxxx = infotype number
Related Notes : 
       
| 320828 | HR-CA-ALE: Link not created in target system | 
| 200343 | HR-CA-ALE: Composite SAP note re distributing HR master data | 
| 200066 | HR-CA-ALE: Q&A for setting up HR ALE scenarios | 
| 119780 | HR-CA-ALE: HR and Application Link Enabling (ALE) |