@jtax thanks again for your thorough response.
I misspoke in my last reply. I originally said, "For every year that ABC was invested in XYZ, there has been a capital loss, ie. Box 8/9 has been negative every year, culminating in 2019 with the complete loss of all ABC's initial capital investment." This is incorrect. Looking back at my previous years K-1's, I see that Box 8/9 have been blank every year. Box 1 has had a negative amount every year. 2019 is the first year that Box 9 has a value in it, after XYZ issued their final K-1 to ABC.
You are correct that there is a passive income limitation here. Looking at Section A, I see a positive number in column (a) Gain (Loss Limited by form 6198), negative number in column (b) Suspended Loss Carryover from Prior Year, a zero in column (c) Net Income (Loss) Allowed, and a negative number in column (d) Loss Suspended for Current Year.
This makes me think that there is no way to use the loss in XYZ towards my 2019 tax returns (I have no other passive income). Only when I dispose of my entire interest in ABC will I be able to use my losses in that tax year. Does this sound correct?
Thanks again for your help. I learn more about our tax system every year.
