To resolve this issue, you can follow these steps:
1. Navigate to Admin > System Setup > Webshop Config
2. Checkout Settings > Enable Drop Shipping Option At Checkout
If this is enabled and the end user Selects "no" for "Send invoice with goods?" on the checkout page, this will trigger a dropship order.
When a product is assigned to a particular warehouse, and if that product is ordered; it gets sent to dropshipper via a datafeed. The data feed only sends orders with orderlines from a pre-defined warehouse.