Sounds correct as long as (1) you started with no IRA and therefore 100% of your IRA consists of your nondeductible ("after tax") money (your "basis"), and therefore 0% is taxable; (2) your earned income (W2 not passive income) is above your traditional IRA contribution amount and therefore eligible to begin with.
Did you put in the 15k non-deductible contribution under Deductions & Credits > Tradition and Roth IRA Contributions, as well as the 1099-R, and answer all the questions e.g. balance of IRAs as of 12/31/24.
This should create a form 8606 with your cost basis and does the math on how much of the Roth conversion is taxable. See if you have a form 8606. Line 8 should have the Roth conversion amount, lines 9-12 figure out the taxable amount, etc.
I'll pause there to see if that helps and you can provide more color on whether you input these things and what your 8606 looks like.
