in step-by-step mode after entering 20Z there should be questions about 199A this is what box 20 Z refers to if you're using the desktop version of Turbotax in forms mode there's a Quickzoom link to enter the 199A info in the Qualified Business Income (QBI) Deduction section which Turbotax does use. forms mode is not available in any of the online versions.
probably you entered 20 Z but did not enter the QBI info which creates a mismatch
