Giant boss in act 2 not attackable on topside of arena

The Giant Boss in act 2 is not attackable if he is at the top of the arena.
Cant talk for range but on melee he was not attackable. Pretty bad if you rely on stun build up and then your whole stun build up drops off because you cant hit the boss anymore. :/

For range, I had a similar issue. This boss has a very weird interaction with projectiles. When boss is on the side, my Bonestorm hits the ground... like in front of me or a little on the side. When I do it right, I see the projectiles fly across to him and see the HP go down faster. I have to be in a certain angle to sometimes hit him and see the projectiles hit. When he is on the top, I had better luck with the projectiles flying across to him and hitting. Longest boss fight of my life as I only had one dmg spell as my minions refused to revive after a certain point in the fight.