Make sure that you have the latest version of TurboTax installed by clicking on Online and then Check for Updates. After doing that, try deleting your 1098s and re-entering them. If you imported them the first time, enter them manually.
TurboTax may be miscalculating your deductible interest based on your entries, but it still would not show $0 if it was due to a miscalculation. Nonetheless, check to make sure that you answered No to Let's see if this is the most recent form for this loan for all but the most recent 1098. Make sure that every loan is secured by your main home.
The only other thing that could be causing none of your mortgage interest to be deductible is if you indicated that you took cash out during a refinance and none of the money was used to buy, build, or improve the home. If you did take cash out during a refinance, answer the follow-up questions carefully. Any portion of the loan used to buy, build, or improve the home is deductible, but any portion used for anything else is not deductible.
