Steps to follow:
1. Click on order log in our app and look for those orders.
If not showing, there that means these Shopify orders are yet to be imported (could be past orders) in app. Click on import order and select the date range / order id to fetch them to our app. You can find them now.
2. If the orders not fulfilled and you want to fulfill them via our app.
Look for those orders in order log and click on Re-submit option "Re-submit to Amazon" for them showing under order log.
3. Upon re-submission the orders should be syncing to Amazon successfully.
(***If there is still some error or orders are still getting rejected by Amazon, review the orders as per the error message and resolve the issue before re-submitting orders again to Amazon FBA.)