Waitlisted but never made the UG list!
This happened before, so you'd think I'd know better. I used a SWU for ORD-LAX. Booked several months back but got waitlisted. When I got to the gate I discovered I wasn't even on the UG list. Went to the RCC. The lady said 23 of 24 F pax had checked in and all were paid F, which I find hard to believe, especially since there were three F seats for sale the day before. I went back to the gate but my name was still not on the board. By this time they had already started boarding.
The lesson is if you're "waitlisted" or "pending" for an UG, that doesn't mean you'll make it on the UG list. Unless you check, you might get an unpleasant surprise at the gate.