Me and more than half of my Guild was trying to get the Bonebreaker achievement past 3 days but with no luck.
Labyrinthine Horror simply never spawns !
We spend many hours in Labyrinth but non of us was able to get one.
Few of my guildies managed to get in at the 1st day of the event but since than he is gone for good.
I noticed this bug on the first day too. It seems to be that, after his initial first spawn (where he pops out of the wall), the Labyrinthine Horror never respawns.
As such, your best bet is to head into the Labyrinth immediately after a new patch where you can be guaranteed of a fresh instance.
Not affiliated with ArenaNet or NCSOFT. No support is provided.
All assets, page layout, visual style belong to ArenaNet and are used solely to replicate the original design and preserve the original look and feel.
Contact /u/e-scrape-artist on reddit if you encounter a bug.