Titan boss is untargetable

The titan boss Zalmarath in titan grotto will become untargetable shortly after the fight starts until he moves. then he briefly becomes targetable before becoming untargetable again.

this issue will persist even through a logout.

When i say untargetable, i mean nothing can connect with him at all no matter what you use or where you aim.

I do not have words to express how aggravating this is.