[CerebroDragon]

*Casts his spell of necromancy*

I'm currently playing the OC for the first time and have just encountered this very same bug - unfortunately the thread doesn't actually state whether or not a solution was found.

The Githyanki in the vault room can't be killed or interacted with in any way. In fact, forced attacks don't seem possible at all. Hopefully I'm missing something very obvious...otherwise I'm just going to try my last save game.

Any ideas?

*edit*.
Upon reloading and doing the archives again, the Githyanki were still immobile and non-interactive in the vault. However, the archive book had strangely appeared so I was able to sneak in, grab the info and continue on to the next part of the main plot.