Animated displacement of rigid body does not collide with other rigid bodies

I am playing with rigid bodies in 2.79 and I’m having the following problem.

I have subdivided a plane a few times, then added subsurface and displace modifiers. I animated
the displacement with a cloud texture and an animated null.
A rigid body physic was also added to the plane (with ‘passive’, ‘animated’, ‘mesh’, and ‘deforming’ selected).

This creates an animated pseudo ocean surface.

I then add a few icospheres in the scene, on top of the plane. They are simply active rigid bodies.

When I do the Free Bake of the Rigid Bodies, the Icospheres instead of interacting with the animated
and displaced plane, they simply rest on the original flat plane.

Am I doing something wrong or displaced animated objects cannot be rigid bodies in Blender?

Many thanks for any comment and advice.