Animation files collapse rig when I import them from blender.

I exported a model from UE4 to animate a couple more things on him. It’s worked before, I simply make a new rig to control the old one using constraints so I don’t add or remove any bones or disrupt the hierarchy.
I’m wondering then why my guy turns into a pancake when I import him back into ue4. (4.25.3)

Ill upload some pictures of the process