back door roth problem with basis

I am having a problem reporting a back door roth conversion.  MAYBE it is due to the glitch that I am reading about that MAY be remedied on 3/31/22, but maybe i am doing something wrong.  My wife's traditional IRA had 14,000 basis at the end of 2020.  i added 7000 in 2021 (bringing the basis up to 21,000).  I converted 15,000 in 2021 to the roth.  My understanding is that the entire conversion should not be taxable since I have more than enough basis to cover the conversion (the basis should go down to $6000 after the conversion).  however, what my TT deluxe is doing is to claim that I have $2863 in non taxable contribution and $12,137 in taxable contribution and the basis for 2021 will be $18,137.  does that sound right to the experts out there or is there a software glitch?