401k IRA to Roth Conversion Taxable Amount

I have a 1099R that I've split. $12k of it was contributions to a Roth 401k from 2019 and 2020 made in 2020 calendar year. $16,556 of it was a rollover conversion to a Roth IRA. I understand from TurboTax help that the single 1099R needs to be split to be able to record the taxable income from the Roth 401k conversion. I have been able to enter these in clearly without issue into TurboTax, but the draft return shows only $14,824 as taxable. I'm unclear why it is deducting $1,732 from the taxable income. I've tried numerous options when adding this 1099R but nothing seems to change the outcome on the final Form 1040 line 4B of on the Form 8606. My age is below 55.