No tax is defaulting from Supplier onto PO created using fbdi upload

We have Suppliers created with a tax classification code at the Supplier Address.

The tax default order is set within the Manage Application Tax Options so that highest priority is Supplier Site and then second priority is Supplier.

When we create the PO using the fbdi upload, the PO is created without any tax lines, even though we have a tax classification code at the Supplier Address that would add tax to the PO line.

The PO stays in "incomplete" status, as there are no tax lines generated.

If we manually edit the PO, and then SAVE it, the tax lines are generated correctly.