UT - Uncollected tax, on the 1040, schedule 2 line 8c is a result of the IRS-W2, box 12, containing a code of:
A - Uncollected social security or RRTA tax on tips.
B - Uncollected Medicare tax on tips.
M - Uncollected social security or RRTA tax on taxable cost of group-term life insurance over $50,000.
N - Uncollected Medicare tax on taxable cost of group-term life insurance over $50,000.

check both the actual w-2 and your w-2 entries.

Entering in the wrong code letter is actually a common data input error  which the program cannot catch since it cannot see the W-2 form in your hand to make sure you entered  the correct code.  If the W-2 was imported then you are responsible for insuring the accuracy of the imported information.  

Once your original return has fully processed you can file an amended return  if the IRS doesn't catch the error for you. 

https://ttlc.intuit.com/community/tax-topics/help/what-do-the-letter-codes-in-box-12-of-my-w-2-mean/...