Invoice accounting status = Partial even though the invoice status is Validated

Hi, Please advise, we have an issue with partially accounted invoices when the invoice status shows Validated. Below are the sequence of events that lead to this issue:

1) Invoice created with self-assessed tax ( Vertex).

2) Invoice is validated fine.

3) Invoice is accounted successfully.

4) After N day(s), the  user updates the Invoice Line, changing the Ship To field and  a DFF to indicate the changes is for overriding the previously created self-assessed tax.

5) User runs the Validation program and the Invoice is placed on a custom hold, which is expected.

6) The User manually releases the custom hold and the Invoice status becomes "Validated".