Guild Wars 2

Did something change about the aggro system lately?
Yesterday I was doing Arah explorable, and one of the bosses was permanently locked onto me. No matter how much I kited around, she wouldn’t change targets. Took 15 minutes or so of me kiting around and the rest of my time hitting the boss, it was stupidly ridiculous.
Today during a champion boss event, the boss was locked onto the same player for the whole fight, without ever changing targets. WTH hell happened to the aggro system? Is this a bug?

I’ve seen behavior like this well before this patch.

I remember when killing a few bosses also. one big char was running in a circle around us and we were just blasting the boss. the boss didnt break off him not once. and it was a melee boss so he never did damage and we just torched him down