Maybe you are now to use Screen 49 for "Voluntary" Prepayments? 

Maybe the program is not yet ready for prime time?

The voluntary payments are simply estimates for cash basis payers that want a current year deduction as estimates aren't required.

Frustrating as the draft note was removed in one of the recent updates so you think they would have fully tested it.  The input field was there in 2020 and now they are apparently using invisible ink 'cause I no see it 😞