Lloyd Simcoe talked of the QED ring being able to tether someone's consciousness to the present time, and keep them from being affected by a blackout. Perhaps there is something different about Tracy's brain that kept her tethered to present time without a ring.
Tracy likely didn't have a flashforward during the GBO, for the same reason she wasn't affected during the blackout test.
Perhaps Tracy isn't really dead, and whatever is different about her that kept her from blacking out will cause her to reawaken before the time of the flashforwards.
Tracy stole, found or was given a ring from Jericho. This explains why she didn't black out and where the missing ring went.
Hellinger could have been telling the truth when he said that every future he saw ended with Mark Benford dead on Flashforward Day. But that doesn't mean it has to happen. Dyson Frost saw March 15th many, many times, and yet it seems he never saw the future that ended up happening (he was standing out in the open, providing an easy target for Alda Hertzog).