Can ffmpeg extract the motion vectors from VP9 videos?

Question

And if it can, are the motion vectors similar to how they are in H264?

I ask because I can run a command like

ffmpeg -y -loglevel error -flags2 +export_mvs -i "$1" -vf codecview=mv=pf+bf+bb /tmp/mot
    ion_vectors.mp4

then view it with VLC and see the motion vectors superimposed upon the video. If I try this with a VP9 encoded video I'm unable to see them.