Schedule A line 23 is exactly where unrecoverable basis in Roth IRA contributions should appear, should you qualify for the deduction. There are many different types of expenses that can appear on line 23, and most, if not all, have nothing to do with business.
Perhaps this has nothing to do with business expenses at all but the IRS simply believes that you do not qualify for this other-expense deduction. For example, they could determine that you don't qualify if they have received a 2016 Form 5498 for a Roth IRA that you own indicating that you did not have a zero balance in Roth IRAs on December 31, 2016, or they can see from all (2016 and earlier) Forms 5498 from your Roth IRAs that the sum of all previous regular and conversion contributions to your Roth IRAs are less that the total gross distributions shown on all code J, T and Q Forms 1099-R and you had no Forms 1099-R indicting rollovers of basis from qualified retirement plans. (The second case determining that you have no unrecoverable basis is a bit of a stretch for the IRS to determine.)
Since TurboTax prepares your tax return based on the information you provide, if you fail to indicate that you had a Roth IRA "open" (had a nonzero balance) on December 31, 2016, TurboTax will can obligingly create this deduction when you don't actually qualify. The same is true if you enter an incorrectly large net basis in Roth IRA contributions or conversions.
