That's unexpected, if she is needed for a questline then she is a mandatory spawn. She can be either working on a console in the interrogation or upgrades room, or on a bench in the room with a big window. Just in case, you can also leave and reenter the station to force a respawn of all of the characters.
The code shouldn’t let that happen, because it forces her to spawn if a quest needs her. The only reason she wouldn’t spawn is if you don’t have her in your pool of characters at all, and I have no idea how someone could get removed from that pool. So, that’s definitely weird.
I’m not quite sure what to do about it though.