No Invoice number using _wcpdf_invoice_number ?

Hello and thanks for a great plugin:

We’ve had success with exporting ORDERS from the old site and importing to the NEW.
However, the Invoice Number is blank when getting imported. We check the export file and that Column “Invoice Number” is missing.

So using wordpress import export default option: Tools >> Export

We were able to get a similar export WITH the Invoice Number using the below tip:

Open section “Setup fields”, click “Add field”, select meta key _wcpdf_invoice_number, fill Column name, click “Confirm” and drag field to left column.

However, we then update/tweak the exported file from your plugin to include the column of Invoice Numbers.

However, when we go to import – that column is ignored/invisible in the import setup screen.

How can we easily do this?