Screaming Goats cannot be bred

A streamer I moderate for spent an entire 3 hour stream attempting to get a screaming goat by breeding them and never got one. I then opened a creative world, summoned a bunch of non-screaming goats and began breeding them for 40 minutes. I then waited for them all to grow up. I then used a kill command to kill only the goats in the world. 213 goats died and not a one was a screaming goat....