I have set up a simple system with a ball (with an attached rigidbody) falling by gravity onto a position locked box (which also has a rigidbody), everything is in the right layers and the physics works correctly. However onCollisionEnter is never called.
Everything has a rigidbody, nothing is marked as a trigger. Both have colliders.
Neither of the objects are kinematic.
Even if I remove constraints on the box or sphere no event is called.
All objects are in the same layer that has physics /collision detection enabled.
It is particularly bizarre as the box /sphere will react to hitting each other, the physics still works but the event is not called.
Can anyone help me work out why it may not be called?