You can experience an issue with the orders failing to import and the error logs showing a message as follows.

There is an invalid reference to QuickBooks Ship Method 'ABC' in the SalesOrder.  QuickBooks error message: Invalid argument.  The specified record does not exist in the list.

You will need to go to the Lists => Customer Lists => Ship Via Lists in Quickbooks and create the Ship Method or change the Freight Company name in The Order Exchange to one that exists in your Quickbooks company