Thanks for dropping by here in the Community, ebartlett.
I'd be more than happy to help you settle the payment that is still showing as overdue in the Pay Liabilities tab.
Before we proceed, I'd like to acknowledge your effort in sharing a very detailed information about your concern and the steps you've done. Since you already made the adjustment to correct the amount that you should be paying for this specific tax, you'll just need to enter a prior payment. That way we can zero out the balance of the tax payment in the Pay Taxes and Liabilities tab. Please refer to this article for entering prior payments in Quickbooks:
If you're have any difficulties with the process, just let me know. I'll zip right back to help you out, ebartlett.