Motion blur with static alembic mesh blurring everything?

Hi,
I've been testing a workflow of using motion blur on alembic meshes in unity following its use in adam. It has worked well for moving abc meshes, but if i have a static object ( eg background ) which is not moving it constantly blurs out.
I believe it is due to some sort of confusion in calculating the motion vectors for objects that do not move, as I have had success overcoming this issue by deforming the point positions with two values before exporting my static abc objects.
However to have to add deformer and offset value to every still object seems odd, am i missing something??

I have attached an image showing the error blur when the abc has no point deformation.