2853312 - Trading Partner is not saved into KNA1/LFA1/BP001-VBUND, or you get a mandatory field error message even when field is filled

1. You try to create or change a BP and you get an error message saying that the trading partner field (VBUND) is mandatory, but the field is filled.
2. You save a BP with the field VBUND filled, and it is saved in BP001-VBUND but this data is not replicated to KNA1-VBUND or LFA1-VBUND, even when there is a customer or vendor linked to the BP, and you might not get any error message.
3. When using the complex interface CVI_EI_INBOUND_MAIN to modify a BP, field VBUND is updated neither in BP001-VBUND even though you pass the value to the following structure:
   I_DATA-PARTNER-FINSERV_DATA-COMMON-DATA-FSBP_CENTRL-VBUND (instead of I_DATA-CUSTOMER-CENTRAL_DATA-CENTRAL-DATA-VBUND / I_DATA-VENDOR-CENTRAL_DATA-CENTRAL-DATA-VBUND) and also pass an "X" to structure I_DATA-PARTNER-FINSERV_DATAX-COMMON-DATA-FSBP_CENTRL-VBUND.
4. During synchronization from customer/vendor to BP, data from KNA1-VBUND or LFA1-VBUND does not copy to BP001-VBUND. 

• SAP S/4HANA
• SAP ERP

"Trading partner: Is a required entry field" CVI_API 003 R1 304 "Required field Trading partner has no entry"  CVI_BDT_ADAPTER 050 or "Supplier-specific data were not saved due to error CVI_API 003 (see long text!)" 051 2830891 ("CVI_VAL: Current standard address of BP not determined resulting in error FSBP_ECC 025 or CVI_API 003" , KBA , CA-FS-CVI , Customer Vendor Integration – FS-BP part , AP-MD-BP-SYN , Business Partner Synchronization , LO-MD-BP-SYN , Synchronization Business Partner with Customer/Vendor , How To