Blanket Sales Order does not have Complete Order functionality when child order is a drop-ship

I have recently reviewed the blanket sales order training document and found that the Complete Order function should be available if the blanket order is in either Open or Expired Status and at least one child order created for a blanket SO line has processed shipment. I have noticed that if the child order is one that is a dropship and is completed, the system is not recognizing this as a type of shipment and is not allowing the blanket order to be completed despite the fact that there is no longer any open qty. Has anyone else found this to be the case?