Having attempted, three times, to complete the Aggressive Infiltration (go in and kill everything and trip every alarm) achievement in Seeds of Truth, I found that it can bug out. The nature of the bug changes — I experienced two issues, both of which occurred in the final chamber with Vorpp. One was a progression blocker that forced me to log out and restart the instance to try it again; the other, I was able to find a workaround for.
ISSUE #1: In Phase 2 of the fight, where you have to disable the shield generator to make Vorpp vulnerable (but before the guard golems appear), I was kiting all the aggroed Arcane Eye Agents around the edge of the central holding cell and killing them off one by one. At some point, I managed to kill the last of them. The fight then stalled; I could see Vorpp’s boss icon on the minimap, but when I went to it, there was nobody there. Without being able to attack him, or interact with anything else, I was unable to continue the fight. The mission tips simply told me to eliminate all attackers to regain stealth, but there was nobody else to kill. I did not find a workaround for this.
ISSUE #2: Again in Phase 2 of the fight, and again whilst kiting the mobs around to kill them off gradually, somehow Vorpp got stuck INSIDE the central holding cell. Instead of zapping around to the generators, he was zapping around inside the cell. This issue occurred twice — the first time, I logged out and restarted because I didn’t think I’d be able to complete it. The second time, I just walked up to the set of bars he was closest to and started attacking. Thanks to the fact that Caithe’s attacks have decent range, I was able to hit him through the bars, and that progressed the fight: he popped out of the cell when his health was low enough, and Phase 3 (shield generators + golems) began and ran normally.
Just a heads-up in case anyone else experiences the same issue and is tearing their hair out trying to work out how to complete it. If he’s invisible, not much you can do. If he’s inside the cell, you have some options, so long as he’s close enough to the bars to hit. :)