If you have a 1099-R with one of the distribution codes being "D" (for example, 4D or 7D), this is a known issue. Please read this TurboTax article and sign up to be notified when there are updates to this situation.
For code 4D, you can indicate that the decedent died after January 1, 1952 even if it's untrue. TurboTax should not even be asking when the decedent was born because it answer is irrelevant with regard to a distribution from a nonqualified plan.
I'm having the same problem with a 1099-R for payments from a NON-qualified annuity. TT insists that I answer whether it is 1) a 403(b) 2) another type of QUALIFIED plan. TT won't accept leaving unless I pick one or the other. Then REVIEW flags it saying that I should have not selected either one. Also same problem with an insurance policy paying dividend reported on 1099-R.
Generally, anything reported on a Form 1099-R is considered to be a distribution from a 'retirement plan'.
If your 1099-R has Codes 4 and D in Box 7, when entering in TurboTax, put 4 on the first line of Box 7, and D for the second line.
Then choose 'other qualified plan'. The income is taxed the same regardless (unless there is a different Taxable Amount in Box 2a). Be sure to enter any amounts in other boxes (such as Box 5) as they appear on your form.
You may want to delete/re-enter your 1099-R, and if you're using TurboTax Online, clear your Cache and Cookies before re-entering.
Here's more info on 1099-R for Pensions, Annuities, Retirement.