In the code, I think I found the cause of this issue. However, I want to make sure my assessment of the fix is correct and prevent myself from introducing (new) breakage.
So, I'm looking for people who use the order/invoice/rfq fields mentioned above. You can help me devise test cases to make sure that if the functionality works for you, it'll keep doing so even after my changes.
Robust and Flexible. No vendor lock-in.