Xesht Wind Serpent's fury bug

At the breach boss Xesht: When I use the wind serpent's fury on it more than one time, the boss always goes inside the wall. Somethimes it is near to the arena so u can hit it with any ranged skill, but sometimes boss goes so deep through to the wall so ranged skills doesn't work anymore. It is kinda annoying to not hitting the boss and dying.