Mmmm I see what you mean. I talked to a UA agent and they said folks ahead of me on the waitlist are "O" fare class hence why I was willing to pay a small difference to move up (its a company-paid ticket), since there are 5 seats avail and I'm 6th on the list lol as a UA Gold. But you're right - no guarantee.

I tried the below itin - am I missing something?