If your sales tax was set up correctly and already assigned on the transactions, and the issue persists. I recommend contacting our QuickBooks Desktop Support Team. They have additional tools to pull up your account and do a remote session to investigate this further.
Here's how to contact our customer support:
Select QuickBooks Desktop Help from the Help menu.
You can also press F1 on your keyboard to bring up the same Help Panel.
In order to route you to the correct support expert, we need to know what type of question you have.
We’ll provide you a few options. You choose which one is best for you.
Please let me know how it goes by adding a comment below. I'll be around to help if you have any other concerns about sales tax. Have a good one.