Problem: Set Animations not Appearing

So, I've been trying to add animations to my mobs. Just simple animations like the preset swing for arms and legs, as well as the head animation. But when I import my model (1.14) it asks if I want to set new animations, but doesn't give me the option to do so. All it says is like "Set New Animations" or "Keep Animations." How do I get it to give me the option to add the preset swing and head animations that Creator has?