The "*" (asterisk) on line 15 means that TurboTax did the calculations on the "Taxable IRA Distributions Worksheet" that is almost the same as the 8606 lines 6-15.
I cannot calculate what the taxable amount should be for your figures without knowing the total 2019 year end aggregate value of all existing Traditional, SEP and SIMPLE IRA accounts that might exist. That will determine how must of the $15K distribution should be taxable.
The interview asks for the prior year non-deductible contributions that you say is zero (the 2019 $6K is already on the 8606 line 1 so it does not get entered again) then then interviews asks for that 2019 year end value of all IRA accounts. The calculations will not be correct without that amount (and yes it will "appear" to lower your refund, or raise the tax owed, because the accurate amounts cannot be calculated without that value.)
The non-deductible $6,000 "basis" must ALWAYS be pro-rated between the current years distribution and the remaining 2019 year end value of the aggravate value of all IRA accounts - you can never withdraw only the basis - so, as long as any IRA account exists, there will always be some remaining basis. Only when all accounts are distributed and closed will the basis become zero.
From your post, I believe that is the problem.
**Disclaimer: This post is for discussion purposes only and is NOT tax advice. The author takes no responsibility for the accuracy of any information in this post.**
