Invoice Header GL Date not changing when invoice swept to new Payables period?

Hi,

We upgraded from 11.5.10.2 to 12.1.3 in November 2014. Since then we have noticed that if an invoice is swept to the next Payables period, the GL Date on the Invoice Lines correctly moves to the next (open) period, but the GL Date at Invoice Header level remains unchanged. As an example:

We had a PO which was receipted on 07/01/15 and an invoice was created via the Pay On Receipt AutoInvoice concurrent program. This invoice showed an Invoice Date of 07/01/15, a Header GL Date of 07/01/15 and a Line GL Date of 07/01/15. When the JAN-15 Payables period was closed, this invoice was awaiting validation and so was swept to FEB-15. After running the Sweep program, the Line GL Date correctly showed as 01/02/15 but the GL Date at Header level still showed as 07/01/15.