The problem goes beyond tech issues.
I sponsored a friend on a "B" fare from HNL-LAX with miles and it didn't clear until moments before flight time.
I have at least 3 itns from SEA/PDX-IAD where I'm using miles and only half have been confirmed. UA is obviously, and somewhat understandably, holding back F seats until the last possible moment for sale.
They're selling every sort of Premier incentive ala carte.