Mocap Mapping Problems

Hello! I’m having some issues mapping mocap data I’ve recorded onto a rigged character. I’ve exported my mocap data in a Mixamo skeleton .bvh, then imported that into Blender - where I have a character who is rigged with another Mixamo skeleton.

I use the Blender mocap retargeting tools to remap the mocap data onto the character skeleton - the limb rotation works fine but the movement of the character in X,Y space is messed up.

This is with advanced retargeting:

This is normal:

The advanced is better, but the feet are not locked to the floor.

Does anyone know what might be causing this? All the bones are remapped to the correct corresponding one on the new skeleton, and the toe bones are marked as the foot ones.