A few times i have encountered bugged out hozen rarespawns. Bonobos, Mr. Ferocious, even the yowler all had this bug.

they just stand there idol. when i try to attack they keep evading all attacks i throw at them. they dont even try to attack me. the only way i've figured out to kill them when in this bugged state is to explosive trap them to death, which on the yowler who was at full health took about an hour to kill.