If this Form 1099-R has been downloaded or entered correctly, the only way that TurboTax would be reporting less of this as taxable than the entire box 1 amount would be if you have basis in nondeductible traditional IRA contributions and TurboTax was preparing Form 8606 Part I to determine the nontaxable amount of the conversion (or if some amount was transferred to charity or to an HSA, but those would be indicated with notations QCD or HSA on line 15b). The calculation on Form 8606 depends on having entered correct amounts used in preparing the form.
