Colossus not taking damage bug + hitbox issue

I had just started the fight in act 2 with the colossus and after about 5% of him taking damage, he became invulnerable for some reason.

In addition, Perfected Strike could not hit him for some reason! I had to go in front of him to see that he gets the damage from this skill! I mean it's a Colossus so I would expect a big hitbox!

Cu guys next patch