If your payment has posted to your bank account, you are fine. TurboTax will always show an 'Amount Due' because that is what your tax return reported. TurboTax does not know whether or not you paid your taxes or got a refund, so it will never change. If you check your 2016 tax return in 2020, it will show the same tax due.
If you want to confirm that your account is in good standing with the IRS, click here: Do I Owe the
IRS