I am happy to have received some replies regarding my situation.
It still seems to me that it is correct that, barring exceptions, the IRS says to leave line 4a blank & enter the total distribution on line 4b, but it’s not the end of the world that TurboTax does things differently.
Regarding the reply from ThomasM125, I take comfort in his reassurance where he says “it won’t affect your taxable income or tax and I can’t imagine the IRS would be concerned about it.”
Regarding the reply from macuser_22, I appreciate the suggestion regarding trying to re-enter the 1099-R. I tried revising exactly as suggested, and the result was the same.
