I routinely wait-list for a mileage upgrade to first EWR to SFO, and sometimes clear just before the 24 hour OLCI window. Every time that this happens, I then cannot check-in for many hours. This is like clockwork. As in, if I could bet $1,000 that this would happen again next time, I wouldn't blink at taking the bet, easy money.

I've been given the obvious explanation by agents, I now don't bother calling.