I've only been playing STO a little bit, had my first space combat and then beamed down to a planet, along with my first bridge officer a vulcan science officer. I got myself a phaser rifle and was discussing kits with an NPC and then I got kicked out of the game by some kind of problem. So I logged back in, the game put me back in that level, and I still had the phaser rifle I had just picked up... but no bridge officer!!!
So now it seems I have to finish the rest of the mission on my own, with no away team backup. And I'm scared to spend any skill points on that bridge officer (the option is still there) in case when I get back to the ship she isn't there either, she's lost forever or something.
I was hit by this same bug tonight and I also reported it. That mission is soloable without the officer. That officer isn't lost. Once I got to my ship after the mission, it was listed in my officer slots and in subsequent missions he accompanied me with no problems. Don't worry.