Have you tried to check if when you import, you transform the meshes nested in the hierarchy into bones? There’s an option under the animation settings, when you import something into UE4 that does this.
Hey, I’m having the exact same problem. No other of my bones are appearing in the mesh but my hand digits and foot digits are - they get given what ever material is in my material 1 slot too… debating just giving them an alt material and hiding them in game. Did you ever figure out how to stop them importing?