An order in Shopify can fail to export to QuickBooks Online for a variety of reasons. If you navigate to Shopify admin -> Apps -> QuickBooks, and select the export date with errors, you'll be able to review the list of orders that failed to export and an explanation for each.
If you need clarification on the reason for the failure or aren't quite sure how to resolve it, please contact our Merchant Success team for help.
Editing Orders in Shopify
Recently, Shopify added the functionality for stores to be able to edit orders that have been made. This includes adjusting customer or product information within the order.
When an order is edited within Shopify, the edits will be unable to transfer to the Quickbooks online app. This means that only the order as it originally occurred will be exported.
Refunds that are made within Shopify will continue to export correctly after the order has been placed.