I have Kylo and Blackout lined up against a B-Wing. The B-Wing selects Kylo as the target. Kylo spends his TL for TT and boosts away. Can the B-Wing still shoot at Blackout or has it wasted its shot?

The timing window for Threat Tracker is when the B-wing becomes the active ship in combat, before it even picks a target.

1 hour ago, Celestial Lizards said:

I have Kylo and Blackout lined up against a B-Wing. The B-Wing selects Kylo as the target. Kylo spends his TL for TT and boosts away. Can the B-Wing still shoot at Blackout or has it wasted its shot?

Also, the B-wing has not "wasted" it's attack, because it hasn't chosen a target yet. It's still free to choose a target (if there's one still in range, that is).