On my IAH-XXX flight, we were 2 and 3 with PPs -and 8 out of 12 booked. Boarding starts in a few hours and it is fully booked and no one has been upgraded. The #1 on the list is still there.
UA still gets most of my domestic travel due to routes, but I have no loyalty. I fly Alaska, AA and DL when it makes sense. And I often buy F. And the inability to upgrade and ridiculous business class prices are why I haven’t flown UA internationally since 2018 or so. It is much easier to upgrade with miles on the European airlines. Plus, the soft product is much better.