I attempt to import invoices, I get the notice: Import invoices isn't quite ready to support sales tax. We're working on it. Support for sales tax will be coming soon.
Hello, Homecook. I understand how important it is to import your invoices.
You'll want to look for a third-party application that can import invoices. This way, you'll have an option to import multiple invoices with QuickBooks Online. Just go to the Apps menu or through the QuickBooks App Centre.
I've got you these resources for additional reference and guide about importing invoice in QBO: