Serveral Bosses are glitched:
Certain bosses are invisible and can only be damaged by certain weapons ie afterburn and explosions, Sentry will target boss but will get 0 damage.
Slow movers such as Mummy and Weeping Angel having no Weapon and has instant start rage.
Serveral bosses don't have starting weapons and have only rage weapons or summons minions, or will be completely civilian