Vector pass only comes out as black

This is on my home PC - on my work PC I get full colour vector passes. Any idea why? I did notice on my home PC that if I add a Normalize node, between the Render Layer and Composite, the vector pass looks like a lighter version of a Z map.

I tried switching to Blender Internal to create a Vector pass, and it worked.

Now here’s where it gets very odd - I then switched back to Cycles and now the Vector Passes work in Cycles too!
Switching to BI seems to have forced Cycles to act properly. Sounds a bit like a bug. Anyone else seen this?

How are you getting a full colour export of a Speed output? I am trying to get this to work for use in AE. What node/s does one have to use to convert Speed to an RGBA image?

If you keyframe e.g. Sphere movement x,y,z during some 20 frames and connect Viewer node to the Speed vector output directly you’ll see speed as a color changes represented in RGB.