Sometimes when I die during the boss fight with the champion unstable abomination during the Bitter Cold story in living world 3 there are vines preventing me from reaccessing the boss.
The only thing I’ve found that allows me to try again is to quit the instance which puts me at the Sorrow’s Eclipse Waypoint and then I have to run back. This is preventing me from finishing the boss fight, mostly because I am terrible at boss battles and keep dying.