The mortgage interest deduction miscalculations are known by some users. Customer Service for TurboTax doesn't understand them.
My recommendation is to enter the data into TurboTax, but before you hit submit, do a manual audit of the tax forms that the software produces. If there are errors, you can correct the numbers on the actual forms.
This issue is frustrating. If I hadn't caught the errors (and amended years of returns), I would have overpaid many thousands of dollars.
Good luck
