Guild Wars 2

Hello i want to ask what is wrong with this event/boss so i can get my achievement.Ive been trying to do it for almost 2 months now and i never see it on,am i just so unlucky or there’s somethin wrong/bug with this event?

pls search before posting: https://forum-en.gw2archive.eu/forum/game/players/Shadow-Behemoth-Event-Devona-s-Rest-Broken/first#post1199930

Just one of many posts bout it.

i m a slacker,i know it but cant help it!