Game-breaking bug with Karolak Nightspinner

[LookitLight]

I'm really surprised this hasn't already been discussed here, but maybe this has just gone under the radar a bit.

Read this post made by a user on the official forums. They reported that Karolak Nightspinner, a boss you encounter during the Celestia storyline, is not appearing in his respective dungeon. I examined this and can say through personal observation that this is not an isolated issue; I experienced this as well, and something is causing Karolak to not spawn.

It seems this issue has gone unanswered by KingsIsle as of yet. I feel this needs more attention, because as it stands this may very well be a game breaking bug with story progression.
@Sparck, @Arthur Wethersfield, @Eric Stormbringer; please take note of this situation and rectify it ASAP.

[Icy Cold Galaxy]

This happened to my friend as well. She eventually had to join a team-up and he appeared then, but she was basically stuck there not being able to summon him for a couple of hours.