TurboTax does calculate the PMI deduction. There are several possible reasons that the deduction might not change your refund. Here are the two most common reasons.
If your AGI is more than $100,000 ($50,000 if married filing separately) the PMI deduction begins to phase out. If your AGI is more than more than $109,000 ($54,500 if married filing separately) the deduction is phased out completely.
If your total itemized deductions are less than your standard deduction, even with the PMI, the PMI will not make any difference in your refund.