Solution : https://service.sap.com/sap/support/notes/492718 (SAP Service marketplace login required)
Key words :
system fills field 'reason, goods movement overview, system deletes, field grund, goods movements, material overview, appears initial, terms co13, cowb_comp-grund, affw-grund
Related Notes :
| 514482 | M7325: Reason cannot be entered during reversal |
| 487200 | Goods movement: No reason in material document |
| 352079 | Automatic goods movements: Reason is missing |