How do you get TT to fill out form 8915E correctly, from a 1099R due to a Covid Roth401k distribution?

This was a Covid related distribution in 2020, box 7 codes were 1B, and box 2a(Taxable Amount) was less than box 1(Gross Distribution) on the 1099R. It seems to work only if I leave box 7 code "B" out and change box 2a to match box 1 amount.