TurboTax generated a Form 2210 based on tax withholding even though after a stock sale I paid estimated tax that covered the shortfall. Is the 85% waiver appropriate?

I have withholding taxes from my monthly retirement income. During 2018 I sold stock which resulted in short term capital gains, for which I then paid estimated tax which more than covered the tax shortfall. TurboTax has generated a Form 2210 and instructed me to check the box for an 85% waiver request.  Form 2210 has calculated shortfall based on the disparity between 2018 tax and withholding taxes, not including estimated tax payments. If not for the estimated tax payment, my withholding taxes would be 74% of tax due. With the estimated tax payment, my total tax payments were 3% more than tax due, resulting in a refund due to me. Why does TurboTax believe that the 85% waiver request is appropriate for me?