Logistics Invoice Verificatio - Wrong vendor brought into FI document

Hi,

We currently have an issue processing an invoice through MIR7.

The current PO line items were entered into MIR7 (ex. Vendor on PO is ABCD). When invoice went through WF, vendor number was changed somehow. PO vendor ABCD, vendor now is EFGH.

We have checked the PO and there are no partner functions put in place in regards to different payee. Checked the vendor master for vendor ABCD has no other payee listed and in the WF, it doesn't look like that changed the vendor master. It looks like the WF picked up the wrong vendor number (ex EFGH instead of the PO vendor of ABCD).

Has anyone ever seen this situation? Any ideas what could have caused this master data change? Any assistance is greatly appreciated.