I was able to confirm that there's an ongoing issue where customers are being charged tax, even when designated as Tax Exempt. Rest assured, our product development team have started their investigation and working on a fix.
In the meantime, let me share some workaround you can try to get you back on track. First, let's make sure the address is updated. If the customer's profile does not have a valid address added, then the tax-exempt status will not apply to any invoices or sales receipts created for the customer.
Here's how to check:
On the left pane, select Sales.
Find and select the customer's name.
In the right corner, click Edit.
Select the Address tab.
Make sure both Billing and Shippingaddress are correct.
If the address is correct, you can remove the check-box for the taxed item, and thus make it non-taxable for that service.
While this is under investigation, I'd encourage contacting one of our phone agents, so you'll be added to the list of affected users. As soon as there are updates, you'll be notified via email. Also, I’ll personally update the thread with any new information or changes related to this.
Thank you for the patience, I'm here if there's anything else you need. Have a great day.