Vector Blur Node not blurring I have a bunch of boxes flying apart in Cycles, and I'm using the Vector Blur node for motion blur. Nothing's blurring.

It's the simplest compositor setup: RenderLayer Image/Z/Speed goes to Vector Blur node Image/Z/Speed, Vector Blur node goes to Comp.Out and Viewer.Out. I've tried all sorts of settings on the VB node, but nothing changes. What have I not set up?

Blend file: https://www.dropbox.com/s/8k6n3cr3wu2iwqo/logo_match.blend?dl=0
This is because the vector pass can't "see" through transparent (glass) objects; in this case all it sees is the lens object, which is remaining motionless relative to the camera.

To render with motion blur in this situation, you'll have to use Cycles' built in motion blur. Enable it in Properties > Render settings > Motion Blur:



And remove the vector blur node in the compositor.