Last night, my team and I ran through Black Drake Villa in an attempt to get the perfecta.
We had spent a bit of time in here, always so close to getting it done before an unfortunate death.
Persistence paid off and we were able to clear the three bosses hard mode variants with no death and in approximately 20mins.
However much to our dismay on our first successful attempt after putting all the pieces together we did not get the achievement.

The last boss, Encratis, died as he was about to port to the other side of the circle due to DOT’s so when we jumped into the pit below and the animation had finished of him teleporting it did not register as a complete.

Here is a video showing what happened
https://gamerdvr.com/gamer/scuzzya/video/150033272

I can assure you that there were no deaths, and we were most certainly within the time constraint.
Not only did we not get the perfecta achievement but two of us did not get the no death achievement either.

I have created a ticket for this, but I don’t like our chances of being rewarded with our achievements.

Has this happened to anyone else?