Hi there, @Jodie RM.
Thanks for taking the time to reach out to the QuickBooks Community. I'm here to share some insights about importing transaction in QuickBooks Online (QBO).
In QBO, there isn't an option to import sales invoice transaction. However, if you're using a third-party application, I encourage you to contact their Care Support so they can provide further information about the process and if you can assign a class when importing sales invoices in QBO.
To learn more about the class tracking feature in QBO, you can visit this article: How to set up and use class and location tracking.
Please know that you're always welcome to post if you have other questions about the class feature or invoice transaction. I'll be around to help. Have a good one.
