Line Type W cost not updating

We are on A9.4.

We entered a sales order and the line has a line type of "W" so a work order header was created. The sales order did go on a C1 hold.

We are able to attach the routing and parts list to the order using P31410. The item being manufactured does require a serial number and we are using actual costing to cost the item.

We are able to complete the WO using super backflush and get the components issued and labor reported. The manufactured item goes in to inventory with the correct cost.

When the WO is completed, the SO gets updated with the next status (from P31114's processing option) and the item's serial number; however, the cost of the item does not get updated—and it should get the cost from P4105 of the item/branch/serial number.