In case this helps someone else, here's what solved the problem for me.
It seems to be a bug in TurboTax Deluxe desktop in how TT deals with K1 20 z entry.
As I described above, I get an error in the final Federal TurboTax checkup which says
"Box 20 Code z has been selected but no Section 199A income has been entered on Statement A"
The error screen then shows the box 20 in question with the z in red even though there is an amount entered for that entry on that very screen!!
It seemed to me that TurboTax just did not transfer the entered amount to the correct form. So, I went to the forms mode and located that K1. The amount that I had entered for Box 20 Code z was blank in the forms mode. So I manually entered it in the form mode. That solved the problem and the Federal TurboTax errors check no longer finds form to have an error.
****I believe this is a bug in TurboTax. Even though an amount is entered for K1 Box 20 Code z during the step by step interview mode, that figure is not transferred correctly to the tax form. Hopefully they will fix this bug soon.
I hope this helps someone else faced with the same problem.
