Form 8915-E Calculations are not correct in TT

After reviewing the Form 8915-E calculations, I found that the calculations are not correct.

For example:

I withdrew $100K and paid back 40% of it, for a total of $40K.

I owe taxes on the $60K I did not repay.

I want to pay taxes on $20K per year, for three years.

TT says I don't owe any additional taxes this year. REALLY???

Once the paid back amount falls to under 33.33%, then TT has me paying additional taxes.

It's like the paid back amount is being multiplied by 3.

Does anyone have an explanation?

Thanks!