I created a skeleton using Blender's rigify, parented an object to the hand bone, created some movement animations, and exported using the Godot Blender Exporter (this generates a Bno.
In Godot, the animations look fine when played directly from the animation player. However, when I set up an AnimationTree with Root Motion, the bone attachment seems to have its own translation equal to the root translation. For example, if the root moves 2 units to the left during an animation, the BoneAttachment's local transform also moves 2 units to the left, so its global translation is actually 4, and it flies out of the characters hand:

Am I doing something wrong? How can I use BoneAttachments and RootMotion together?
The attached zip contains the blend, escn, and tscn files.
This is Godot 3.2 on Linux, and the latest escn exporter.
Thanks in advance!