I erroneously put $0 paid in 4868. When I update amount paid w extension in amendment, TT doesn't calc refund (unless I enter as an estimated tax payment). How do I fix?

-I filed form 4868 in May 2020, and erroneously put $0 paid instead of the large amount I actually paid.  I did not catch this error (embarrassing)  before e-filing.
-I am amending my return to get a refund, but when I change "amount paid with extension" in TurboTax to the actual amount I paid, the amount of my tax/refund due does not change.  The only way I can get TT to calculate that I am now due a refund is to instead enter the amount I paid with my extension as an estimated tax payment.

How can I make TurboTax take into account the corrected amount I paid?