Apologies for bumping an old post but a friend and I have experienced this same issue and I wanted to keep everything in one place.
Teq and Blightgast use the same model, or at least look alike.
As for the bug, it’s happened to a friend and I twice. Both of the times she opened the instance and I joined her, once with a character who had finished the campaign and once with a character also at the claw island step. Both times it has bugged out.
The mission goes as normal up to the appearance of Ol Blighty himself (itself?). The cutscene plays as normal, but afterwards he (it?) is absent. The wall has disappeared (in its usual, slightly buggy, manner, with things that had been on top of the now absent sections still up there) but there is no dragon visible, and no further objectives are given. The first time we encountered this we blamed Trahearne and then gave up.
In today’s run I accidentally found out how to fix this. It seems like (amongst other things) a script isn’t firing properly, as I went over to Blighty’s spot to investigate and poof! the dragon pops into view, as if by magic (and/or as if the lod information for him is iffy). He roared at me and reared on his hind legs, my character spent several seconds running into a wall due to the fear, and the mission finally proceeded as it should.
With the minor exception that Blighty was still not visible from the entrance-side of Claw Island.
