Intercompany customers and vendors are entity records used only for Intercompany transactions. When you create a work order from an Intercompany Sales Order it is just a regular non-intercompany transaction. Currently, NetSuite only support Intercompany dropship orders but not Intercompany work orders.
To build a Work order record from the Intercompany Sales Order created from Intercompany Purchase Orders:
1. Edit Intercompany Sales Order
2. Under Items tab > Unmark CREATE WO checkbox > Click Save
3. On intercompany Sales Order, click on the item line Work Order link.
4. On the Work Order, remove the Intercompany Customer which defaulted from the Intercompany Sales Order where it was created from.
5. Leave Customer field = blank ( if the field is mandatory, select a another customer name)
6. Click Save.
Note: Related to Enhancement 336760 – Intercompany Sales Order > Work Order > You can add inventory, assembly, or kit/package items only to intercompany transactions generated from purchase orders. Add the ability to automatically create Work Orders.