What do i put in box 2 for outstanding mortgage principal as of 1/1/2018 if my mortgage payments didnt start until feburary?

Ok ... either enter nothing at all if allowed   or put a ZERO ... if you didn't have a mortgage until Feb 2018 then the beginning balance on 1/1/2018 would have to be zero. 

If I enter 0, which is shown on my 1098, then turbotax doesn't deduct my mortgage interest paid. If I enter the correct amount for the outstanding mortgage principle then turbotax recognizes the mortgage interest deduction. My lender said my 1098 was correct and that box 2 should be 0, but I don't think that is correct because when I enter the info that way I can't use the mortgage interest deduction. Please advise!!