Cannot hit Colossal Guardian boss in T4 map

Bug Report ID: #3514953424

After reducing the colossal guardian boss down to about 90% health, he is no longer able to be hit or damaged by my spells. My wither aura still stacks on him, but no attacks can target him, nor is he affected by AoE attacks. The spells I was using are Despair (with cursed ground, burning inscription, and impending doom), Contagion, Essence Drain, Dark Effigy, and Flame Wall.

Same
https://streamable.com/ub4vs5
:C i can't win

I just had this same issue. Works normally for a few seconds then suddenly boss is not targetable by melee strikes, stampede, hammer of the gods and boss is no longer affcted by my Xoph's Blood Amber Amulet.