A couple things to check out:
First, be sure to double check
how you entered your mortgage information on all the screens in
TurboTax. For example, if you do not select that the mortgage is
secured by a property of yours, the interest will not be included as a
deduction in your itemized expenses.
Second, the ability to deduct mortgage interest is much more restricted in 2018. See more information below:
https://ttlc.intuit.com/replies/3300473
