I used my HSA in 2017 to reimburse PRIOR year medical expenses. I got a 1099-SA for this amount, but TurboTax is deducting it from my 2017 medical expenses. Why?

I held off reimbursing myself for several years from my HSA, but finally did so for several prior years expenses in 2017. My 1099-SA shows the amount withdrawn, which I entered into TurboTax. Now, TT is subtracting this amount from my 2017 medical expenses, making me lose their deductibility. Why are prior year reimbursements being used to shrink my 2017 deductions, and how can I fix this problem, please?