Reposition Unreal Skeleton Bones?

I have a humanoid mesh that doesn’t match the Unreal skeleton, I thought I could simply reposition the bones within 3ds max and then retarget within Unreal, but for some reason whenever I enable ‘Bone Edit Mode’ in 3ds’ bone tools the bones completely break when I try to move them.

This happens no matter what bone I move. I created a new bone chain and tested the same thing and it works as intended, only the bone I move actually moves and the children maintain the position. Any help is appreciated!

Bump, anyone?