I appreciate your attention to my plight. Perhaps I was not clear. I did include Line 20 Code Z in the K-1 interview. The interview is indeed presenting the "We need some information about your 199A income" dialogue in which one checks the applicable checkboxes, each revealing its relevant fields. The problem is that in my case, that dialogue omits W-2 wages and UBIA. Please see the first of the images I included in my Post.
Thanks for what you said about 20AB.
