Why won't TurboTax Online accept the amounts I enter about my 2019 state refund on the"tell us about your refund" screen and reject amounts entered as less than zero?

Regarding entering my 2019 state refund, the program will not advance beyond the "Tell us about your refund" screen. It reloads the same page with the messages "Refund amount can't be less than 0 (zero) and "Total Payment amount has to be 0 or more." I entered positive numbers in both boxes.