The 20% QBI deduction will be reported on line 9 of your 1040 form. See the last link below for steps to preview your 1040 form.
In order for the K-1 detail to be included in a QBI deduction, there must be amounts in Box 17 of the SCorp K-1 form with codes in the range of V to Z. If your K-1 form has amounts in Box 17 with these codes, then be sure to get all the way through the K-1 form entry section in TurboTax in order for the QBI deduction to calculate.
If there is still not a deduction reflected on your 1040 form, note that there are exclusions to Specified Service Trade or Businesses when taxable income amounts are above the thresholds of $207,500 for single and $415,000 for joint filers. In addition, certain rental activity is also excluded from the QBI deduction. See more detail in the second link below.
You can read more information about the QBI deduction here:
https://ttlc.intuit.com/replies/7019998
https://ttlc.intuit.com/replies/7122193
Here is information on how to preview your tax return before filing in TurboTax online versions:
https://ttlc.intuit.com/replies/3302322
