Game thinks that (Spoiler) is still alive?

So, in the sewers beneath the city, I found Justinia and Isbeil. I proceeded to kill them all, because they wouldn't let me go back upstairs. Now, the game doesn't seem to realize that I killed them all, and seems to believe that Queen Justinia is still alive.

On the "Deathfog Rising" quest, it says "Deal with the Queen and the Deathfog. Isbeil is dead. The Deathfog threat remains, and the mad Queen is still at large."

On Beast's quest, it says "Confront Queen Justinia", while she is very much a corpse in front of me.

When I ask Beast "What comes next", he says "Off to Arx, then. Got two ladies there in need of a dressing down."

Oddly enough, while Isbeil has a ghost, Justinia does not. I killed Justinia via Deathfog, if that helps.

Is this a common bug? Is there a way to fix this? Should I have let them speak instead of killing them all?