I finally found the error. The problem was with TT software from 2018; it definitely made an error in calculation of my QBI, reporting a loss (and hence no deduction), when actually I had a gain in 2018.
But apparently Intuit caught the problem somewhere along the line, because when I launched my old 2018 software it did an update and then correspondingly CHANGED the entries and calculations. I know this because I still have the printed copy of my return from 2018, and the 2018 software now has different - but correct - entries, versus my old printed copy from last year. The software now reports that I actually qualified for a higher refund last year because of this error (wish I had caught that last year).
Now the problem is, my 2019 software had already transferred my information from the previous year before the update to 2018, so it pulled the incorrect information, and I can't see a way to get my 2019 software to "re-transfer" the correct info. If I do a manual over-ride, it won't permit me to e-file. But if I don't get the correct info transferred, then once again this year I will lose some of my refund again this year.
So, bottom line is that the error in the 2018 software cost me some refund both in 2018 and again in 2019!
Now my
