section 1256 gains and losses are first reported on form 6781. then the amounts are carried to schedule D lines 4 and 11. I do not know if Turbotax can correctly import section 1256 transactions.
you don't have to report the details according to IRS instructions - just the "1099-B" in column (a) and what is on line 11
see the instructions for line 1
https://www.irs.gov/pub/irs-pdf/f6781.pdf