Purchase order document status update (from "INCOMPLETE" --> "CLOSED FOR RECEIVING")

I am creating Purchase Order (PO) via FBDI. We either "NONE" or "BYPASS" in the FBDI header tab "Approval Action" coloumn as per the attached screenshot: "FBDI_PO_HEADERS_INTERFACE_tab.png". While submitting the ESS Import Job we bypass the Approval and PO get created in "INCOMPLETE" or "CLOSED FOR RECEIVING" as document_status as per the screenshot: "fbdi_created_PO_in_table.png".

I need to update the Buyer(agent_id) of the both PO. It was succeeded for the PO with INCOMPLETE but the same RESTapi did not work for the PO with "CLOSED FOR RECEIVING". This is still ok.