Black Barya Unspawn bug

I was fighting the Boss from Black Barya Fragment and he just run away from the fight,instead to enter on second wave, after the tornado attack, he just run unspawn. It still saying 1 monster remain, but he just unspawn from the arena.

I was not recording at the time but I made a little video about how the arena was after the bug.


https://www.youtube.com/watch?v=nM4cVhos9PY