Thank you for the screenshot! Can you confirm for me what state your business is located in?
I wonder if the issue is that you may only need to be collecting taxes in specific states based on where you are registered. If the product prices are set to include taxes, and you charge taxes when eligible, then states that don’t have taxes they need to pay would see the product price less the tax rate. Hence the deducted price once the customer enters their shipping address from outside of your businesses state.