I’m not sure if this is a glitch or it’s what really happens but I usually carry one into a wooden taming pen and leave it there for a while. While waiting I go do random things, like kill a bunch of things at Carno Island/The Dead Island for some XP. After around 15-30 minutes I go back and knock it out and give it some Gallimimus Egg Kibble. As soon as I put the kibble in its inventory it tamed immediately. A new way to starve tame I guess? Also there were no corpses or anything in the pen to feed them.