Why doesn't TurboTax recalculate the taxes owed due to 1099-R Minimum Required Distribution after entering the amount of roll back as reported on Form 5498?

I rolled back my Required Minimum Distribution and after entering my 1099-R taxable amount, Turbotax asks if I rolled the distribution back into my IRA. After answering that I did roll back the entire distribution Turbotax erroneously fails to recalculate the taxes owed.  If I force the recalculation by entering 0 into line of 2a on the 1099-R, the amount of taxes owed drops substantially.