Hello,
I don't get the hidden achievement "A Brotherhood's Best Friend "
After the final battle in the Gyala Delves Meta you can headpat the Jade Behemoth to get the achiev. I did this several time with different chars and relogged... no result. I took part in the meta and checked my achievements from "What lies within" several time.
ANet doesn't help and told me to post a bug report. So anyone experienced that too?