SoU - Dark wind bug - Becoming immortal

[Redneiw]

Has anyone else experienced the immortality bug when fighting for the dead wind in the plane of shadows?
I've played the game a couple of times and experienced the same bug on several characters.
Can't remember all but I think i've been playing a melee fighter / blackguard or something most of the times.
Not really a problem since the fight becomes a walk in the park but would be interesting if anyone else has experienced this bug.