The Zero Rated Tax coded selected in the tool is incorrect and the invoices failed to sync into Quickbooks for that reason.
If on the old older version of our SyncTool and select the entity. On the "Quickbooks" tab select "Edit" in the bottom left corner.
In the "Zero Rated Tax Code" field you have the incorrect value entered. Where you see the "." please delete it and add "none" if you're using US Quickbooks.
For other regions such as Canada for example: You can find the Zero Rated Tax Code by opening Quickbooks and going to the "Sales Tax" tab and "Manage Sales Tax".
Here you'll find the Code for Zero Rated Tax. By default it's set to "Z" but may have been changed.
For more the latest SyncTool, it will be under the Integration Tab.