Guild Wars 2

I have defeated the new “Unbound Guardian”, and didn’t got the achievement.

Anet, please point me, where did I spoil this, what should I do and don’t do next time to get the achi. I have partcipated from 80%, and made dps, got the end chest, etc.
Next time should I do some pray, incatation or something, or just forget to get the achi, I haven’t deserve this.

Correct would be if you would make that achi valid on my account.

I did not get this on my first try either but I did the second time. The first time I did not know how to utilize the green circles that he spawned but the second time I did. I have no idea if that is what helped me get the achieve.

I have heard others say they completed all the prior events as well as this one and did not get it and others have said it took several tries before they got it. Definitely seems hit or miss.