Timelost Sanctum - Gareth Isn't Here?

I'm a lvl 62 assassin, and I was catching up on some old quests and dungeons I just never did.

Anyway, I was going through Timeliest Sanctum, and everything works fine until I reach the boss room. The intense music plays, but Garoth just isn't there, and there's no way to get out of the boss room but to relog or die somehow.

So I relogged, and that sent me out of the dungeon, so I used another key and tried again, but it just resulted in the same issue.

Has this happened to anyone else? does anyone know how to fix it, because I'd like to finish the dungeon, but that's quite impossible at the moment.

He just gone:

Thanks!

EDIT: I waited for like 30 mins and he eventually just appeared :/
Think it's just some obscure bug I ran into lol.

 

I think that he just took a break, let him be

 

I had that problem too, yeah it is a bug, and they claimed it was fixed not too long ago.