11.5.10.2 AP - Update Invoice Header issue

Hi,

I have a customer who says that until last week, they used to be able to go into invoices in their 11.5.10.2 system, and change the invoice header details (e.g. Invoice Date, Site etc).

They provided a screenshot of a sample invoice - e.g. below

They have their "Payables Accounting Process" running every day at midnight and it has been running like that for years.

They have not applied and patches recently, and have not changed any profiles.

I checked on a new invoice created today, where Accounted = No, and I can update the header.

From the example above, which shows as partially accounted, would others expect that you should not be able to change the invoice header?