Solution : https://service.sap.com/sap/support/notes/1440153 (SAP Service marketplace login required)
Key words :
attached correction instructions automatically, function module 'crm_ipm_datasrc_valtyp2bval', current item guid, quantity pricing case, ipm billing document, pricing document, billing document, data values, negative quantities, side effect
Related Notes :
| 993524 | Incorrect +/- sign for negative quantity (returns) |