Alright, I admit my mistake in understanding the condition of Zoey's leap, I don't watch Revenge as much because while I enjoy the evil leapers I felt they took it too far making Zoey a leaper.
I however don't believe success was vital to how immediate her leap out was. This is why:
In Deliver Us from Evil, they were leaped out immediately upon failure. In Return Of The Evil Leaper, Zoey demanded Alia's removal though there could have still been room for success. When Sam leaped out the real Arnold would have returned where he'd be accessible by Alia for termination. It's made clear that Arnold was her assignment not Sam as it's directly revealed that they were initially unaware that the Arnold they were dealing with was in fact Sam.
As I said, their leaps are controlled, they can be extracted whenever desired. The reason Zoey probably wasn't immediately was because Alia's leap out had perplexed the Evil Project. In between Alia's leap out and Zoey catching the second bullet Thames had been pressing buttons on his handlink frantically trying to figure out what had happened to Alia. Thus not giving the command as Zoey did in the previous episode to have Zoey extracted. Then she was killed (if memory serves) thus that is probably what ended up triggering the leap.
In fact since they wouldn't be able to lock on to Alia from that point on, they probably never knew whether she'd caught that bullet or not thus nor if Zoey succeeded or failed.
It is? Wait, are you referring to their not being able to retrieve her after she leaped out in Revenge?
I guess that what he/she meant was that Alia was lost in time from the beginning, just as Sam was, and that's why they couldn't get her back.
By the way, I don't believe Alia is dead, either. She just went on and lived a normal life away from Zoey and Lothos and perhaps even from the leaps themselves. That's why she was free.