One problem that I have had is that when I have printed boarding passes for a flight within 24 hours of departure and my uppie has not cleared, is that I have overlooked checking the box that I still want an uppie. One of the GAs pointed this out when I was not on the uppie list. After reinstating me, I went right to the top.

So make sure if you don't get your uppie and you print up the boarding pass, check the box that you still want one.