This bug is currently being investigated.
If box 7 of this Form 1099-R has codes 4 and D, indicate that the decedent was born after December 31, 1951. The date of birth is irrelevant to the reporting of a Form 1099-R with code 4 and D in box 7, so TurboTax shouldn't even be asking about the decedent's age.
If the Form 1099-R has codes 7 and D in box 7 there is nothing you can do but wait for the bug fix or print and mail your tax return.