I have had a bunch of flights lately not clear until very close to departure, even though R>0 ever since the booking window opened. Is there anything that can be done? I've called united on a few of them and they just say it's "automatic" and they can't do anything.

A good example is DEN-SEA on 4/30. R=9 and has been that way since the booking window opened, and now we're just 1.5 days away. The longer these flights sit at R>0 the more chance for first class seats to go away with upgrade instruments.