Arbiter of ash bug.

So I finished the phase where you run from safe circle to safe circle. It sounded like the boss then started the safe 'lane' phase, but it instead spawned a circle just like the safe circle phase. I ran into it, and then the lane phase went instead, killing me. There were no lanes until right when it procced, and the circle didn't explode so I'm assuming this was a bug?

Because honestly man if not, the attempt before I got the really cool 'stand in the safe circle and eat the entire one shot beam because if you leave the circle you're dead' part.

Worst boss fight in the game by far.