How to Prevent Work Order Creation for ATO Item When Manufacturing Is Managed Outside Oracle Fusion

We are using Oracle Fusion Order Management and have several ATO (Assemble-to-Order) items. In our current setup, manufacturing is not implemented in Oracle Fusion—instead, manufacturing is managed in an external application. Our process is to submit the sales order in Fusion, then interface the order details to the external manufacturing system for fulfillment.

However, when we submit a sales order for an ATO item, Oracle Fusion attempts to generate a work order based on the GOP (Global Order Promising) sourcing rules. Since there is no manufacturing plant set up in Fusion, we receive the following error:

Order promising can't schedule the fulfillment line because sourcing for the item isn't set up correctly. (DOO-2685281) Details: Make sure you correctly set up and assign your sourcing rule, and refresh the Order Promising server.