Simulacrum Issues

Was finishing my Simulacrum run for the first time and killed both final bosses on wave 15/15, but the game thinks one of the bosses is still alive despite both seemingly dead with no health bar? one of the boss character models seems to be standing still grunting and moaning at me as if i didnt drudge though 15 waves for a final reward only to be left listening to this guy huff and puff??? anyone know what i missed out on by the final wave not completing? I have screenshot and screen record if helpful. OOF!