If you are missing orders in XPS when using Quickbooks Online, with no error showing this means one of the shipping fields within the Quickbooks Online invoice has been filled in.
Quickbooks Online invoices have 3 fields for shipping:
Shipping Via
Ship Date
Tracking Number
If any of the shipping fields within the Quickbooks Online invoice contain any information, the platform will not show the order assuming it has been shipped.
To resolve the issue, you will need to edit the Quickbooks Online invoice by removing the information shown in the shipping fields.
After removing the information from the shipping fields in the Quickbooks Online invoice, return to XPS, and re-sync the orders from the Ship screen.