A taxable 403b to a Roth IRA conversion was treated as a non-taxable rollover by TurboTax even though the 1099R information was correct. How do I correct this?

I converted money from a 403b to a Roth IRA, which should be taxable. The correct taxable amount is in box 2a of the 1099-R and the correct distribution code G is in box 7 according to IRS instructions. However, TurboTax does not treat this as taxable income and the word "ROLLOVER" is printed on line 4b "taxable amount" of the 1040 form. How do I correct this? " I can get it to treat it as taxable if I put the incorrect distribution code (e.g. "normal distribution") in box 7.