Particle Collision bug?

Here you have one base mesh, 2 emitter surfaces using the same particle system - thus using the same 3d object for the particles.

What is strange is that one accepts the collision command (left) and the other (right) does not.

This doesn’t really make sense because mesh and particle data are shared.

Are all objects in the same layer?

Interesting - this is doing the job sometimes. Is this on purpose to be layer dependent?