TurboTax will adjust the deductible mortgage if your outstanding mortgage principal exceeds $750,000 on homes purchased after December 15, 2017, or $1 million on homes purchased before that, even if you have refinanced since then. If the limit is not being applied to your mortgage, check your answer to Let's see if this is the most recent form for this loan. TurboTax only calculates the limit based on loans currently outstanding.
If that does not seem to be the issue, you can try deleting Form 1098 and re-entering it.
