Root Motion not moving character


I’ve looked through several topics, but none could help me with this:

  • I have a simple skeletal mesh
    (exported from Blender 2.78, via FBX
    version 7.4 binary).
  • Said mesh has a simple animation
    moving the root bone (forward
    movement along the y axis).
  • I imported both into UE4.12, opened
    the animation asset and enabled Root
  • The mesh animates in place, so the
    root motion is recognized I guess.
  • With the animation asset I then
    created a montage on a custom slot.
  • I created an animation blueprint,
    with only said custom slot feeding
    the final pose. The animation Blueprint is also getting Root Motion from Montages only (though switching to “Everything” doesn’t change the outcome)
  • I call the animation blueprint (via
    event) from a character blueprint
    (with assigned mesh/animation BP) to
    play the montage every 1.5 seconds.

So far so good, HOWEVER: When I start the game, the montage plays, but the character doesn’t move.
I’m really not sure what could cause this problem.
I hope someone can help me with this.

Actually got it working now.
Turns out I got a warning on the skeletal mesh import:

"Warning The bone size is too small to create Physics Asset from Skeletal Mesh . You will have to create physics asset manually"

And apparently if your bones are too small for physics assets, they are also too small for root motion.
Anyway, this whole thing is an issue with Blender’s FBX export. You gotta rescale your mesh/armature according to the steps in this problem description:

After that the warning should be gone Root Motion should (also) work out fine.

Blender adds object to bones as root.
So root bone become a second bone.

Edit exporter of Blender.


Line 2477 connections.append((b"OO", get_fbx_uuid_from_key(empty_key), ob_obj.fbx_uuid, None))

This code causes this problem.
Delete or comment out it