Deformation Motion Blur and Vector Pass not working in Cycles I'm experiencing an odd behavior with deformation blur in Cycles with an specific model of an elephant even in a new scene.

When rendering with Motion Blur enabled I've got this render with only blur in its hair strands:


Here you have a render without Motion Blur for comparison:


The weird thing here is that if I add a new object and deform it with an armature, I do have the motion blur. But that's not all: if I render without MB, the geometry is missing from the Vector Pass!!! Only the strands are visible:
 

I've checked if I have a full Vector Pass in the Internal engine and I do:


The object have Motion Blur and Deformation enabled... I would like to share the file but I cannot as it is a Turbosquid model although I can share any screenshot. But normals are right, it doesn't work without the modifiers either or if I erase everything an apply an armature from the ground... 

Do I missing something?
The model has active Auto Smooth Normals. Disabling it fix the problem.



It was a purchased model and it appears that Blender activated Auto Smooth when importing the FBX model.