Motion vectors on alembic break when applying new material??

Hey,

I'm having an issue with motion vectors. I am using alembic mesh for animation following the adam workflow for motion vectors on abc mesh.
This works fine with the default material assigned which comes in with the alembic import. However when I apply a new material to the alembic shape node I seem to break this connection. Has anyone found a solution to this?

example image includes two abc cubes with animation. The white cube has the default material still assigned, but the green cube has had a new material assigned to the shape node and the vectosr are no longer showing.

Thanks

 

So in-case anyone else comes across this, I found the solution. I was not using the alembic shaders provided with the plugin. These shaders are essential in calculating the motion vectors.