Facebook orders that come into Shopify work differently than direct sales. The difference is how the payment is captured. In order for the Shopify orders placed via Facebook to populate into XPS Ship, follow the steps below to turn on the "Payment authorized" setting, and the option to re-download all orders in your integration settings:
Select the Settings tab.
Under “eCommerce” select “eCommerce Integrations”.
A list of your current integrations will appear, select your Shopify integration.
Under Shopify Settings, check the boxes for “Include orders that are in Payment authorized status” and "Redownload all orders on next sync".
Select "Save Changes" at the bottom.
If you are still not seeing the orders after enabling this setting, it could be not enough time has passed. When an order is placed through Facebook, in order to allow the payment to be captured, it changes the order status to "On-hold". The status is normally updated from "On-hold" to "Payment authorized" within 4 hours, however, it can take up to 24 hours. If the order status has been on hold for longer than 24 hours, you will need to reach out to Shopify Customer Service. For more information visit the Help Center Article: Processing orders from Checkout on Facebook and Instagram Shopify Help Center