Exported rig reduced to 1 bone in physics asset editor

I’m exporting a rigged mesh with 3 bones into UE4. When I right click the mesh and choose to create Physics Asset, it takes me to the physics asset editor and there the mesh appears with only one bone. It does recognize the other two bones, but it’s like the first bone has taken over their parts of the rig as well, meaning the entire mesh has only one bone attached to it and so can’t really move or bend at all. How do I fix this issue?
I’m using Blender 2.79. I see other people exporting from 3dsmax and having no problem whatsoever. This is not for animation. The bones are rigged to the mesh with vertex groups and weights. It’s a beard I want to child to a character and have it move and sway naturally

*recorded animation