I had no NOL in 2016 yet TT automatically filled in a number for it in 2017. Where do I find justification?

TT may have made mistake? I can't find any carryover in my 2016 TT forms. I had a refund in 2016 but no losses to carryover anywhere. Now in 2017 TT is asking me to explain the prior carryover. I can't.  Any suggestions?