While importing the vendor invoice lines using the lines entity. So the PO number field should still be populated in the same way as for a manually processed invoice. The way the functionality works at present, this field behaves differently for manually created invoice lines vs imported invoice lines.

Without this, the AP invoice automation is not usable as the imported invoices will not show the PO number once they are posted. This will cause us problems with analytics and reporting as we will not be able relate posted invoices to the PO. Also users will not be able to filter/search posted invoices by PO.