Hi @fccoc,
For your information: In order to create a smart bundle that includes bundled products with different tax rates, your bundle must use the auto-calculated price, not the manual price (price entered in the General tab). Then, when you add products (with predefined tax rates on their own product page) to a smart bundle, the tax rates will be auto-calculated into the bundle’s total. When using the manual price, tax can only be applied to the main bundle as it is difficult to properly distribute the total to each bundled product.
I have checked the tax calculation on our test site with only our WPCstore, WooCommerce and our plugin. Everything is working just fine.
If you are using an external plugin to manage the tax calculation on your site, I am afraid this is a conflict with third-party elements.
For further reference, you can refer to our online documentation here: https://doc.wpclever.net/woosb/.
We offer a free customization service for Premium users, so if you need help with external plugin conflicts, kindly contact our developer at our Support Forum.
Best regards.