Cannot change a price and split a shipment at the same time

As a supplier if I go request a change, when go to the PO lines section, I'm changing the price, then I go to the shipments section and I split the shipment into 2 shipment with different dates.  I get a message that the PO Line price cannot be different from the PO shipment price.  However, the PO shipment price is greyed out so I can't change it.

I don't have any personalizations on that form so assume this is standard Oracle functionality?  Can someone confirm?

Seems like this makes the supplier go through hoops to request changes.  First they have to ask for a price change and then once that returns from "Supplier Change Pending", then they will have to request a split shipment with different promise dates.