Clicking on mesh is not detected at some points

Mesh is not recognized when I try to "pick" it at some points.

I created this PG where each click adds to the counter, so it's easy to notice when a click is not detected.

http://www.babylonjs-playground.com/#NEPU6C#8

Here's also a video demonstrating the issue - notice the counter as I click at different points on the mesh.  On most points it works as expected, on some it doesn't.