Another data point -
I tried to do the waitlist for premium award and was rebuffed 2x (phone and chat)
It is a 3 leg international business saver award with 1 international partner leg in X, a second international partner leg in I, and a United-operated domestic leg in X. Should be eligible for a waitlisted premium award for the third leg.
Both agents said that because it was a mixed cabin business award, I would have to pay way more miles to be confirmed into business (from 88k- 440k). Me pointing out that is was already a business class ticket got nowhere.
Conflicts with the info from Twitter above, but seems to be in line with the new training to deny now that they have moved 100% to dynamic awards.