Internal Sales Order transfer pricing

We are upgrading from 11.5.10.2 to12.1.3 and I'm testing the Internal Requisition / Internal Sales Order process. We use ISO to transfer goods from our central warehouse to local warehouses and offices so all the customer, supplier relationships, shipping networks etc are all in place. We have a nominal price list header with no items and prices on it called Internal as per the documentation "A price list needs to be defaulted during order processing but there is no validation during the internal order process. This price list must be associated with the customer address setup earlier. The items are transferred