APXINWKB: FRM-40105 ERROR AFTER MULTIPLE UPDATES OF AP INVOICE HEADER DFF

Hi,

I have enabled AP Invoice Header DFF and I am facing following issue.

Scenario
1 - Display an AP invoice in the invoice workbench

2 - Click the header flexfield and update. Save changes.

3 - Without re-querying invoice, update any header flexfield (i.e. a second flexfield update), then click Ok to save changes. Results:
(a) In invoice summary block, cursor moves to the next row, effectively creating a new invoice
(b) Error message is displayed in the APXINWKB status bar:
FRM-40105: Unable to resolve reference to item

4 - Click back on the original invoice, get message box with this error: