3796232 - api_supplierinvoice_process_srv returns m8/375 mandatory field 'ReferenceDocument, -fiscalyear, -item' when creating supplier invoice

• An error occurs when attempting to create a supplier invoice via API_SUPPLIERINVOICE_PROCESS_SRV.
• Error message: "M8/375 Fill in mandatory field 'ReferenceDocument, -FiscalYear, -Item' ".
• The same payload structure previously succeeded but now fails with the mandatory-field error.
• Service metadata does not mark ReferenceDocument, ReferenceDocumentFiscalYear, and ReferenceDocumentItem as mandatory.

• BAPI (Public Cloud)

API_SUPPLIERINVOICE_PROCESS_SRV, supplier invoice, M8/375, mandatory field, ReferenceDocument, ReferenceDocumentFiscalYear, ReferenceDocumentItem, purchase order reference, to_SuplrInvcItemPurOrdRef, OData, goods receipt, GR-based IV, invoice creation error, metadata nullable, posting failure , KBA , MM-IV-LIV-BAPI-2CL , BAPI (Public Cloud) , Problem