Problem with colliding instances of same object

I want to check if object's instance is overlapping with another instance (any spawned object with another spawned object, not necessary the same object). I'm doing this by detecting collisions between bodies. But I have a problem. Spawned object (instances) are detecting collision with everything but other spawned objects. I've checked collision layers etc. All of spawned objects have rigidbodies and mesh colliders. Also when I attach my script to another body and I touch that body with an instanced object it detects collision. So problem is visible only in collision between spawned objects.

     void OnCollisionEnter(Collision collision) {
                 if (true) {
                     //    foreach (Transform child in this.transform) {
                                 //        if (child.name == "Cylinder") {
 
 
                                 //collided = true;
                                 Color c;
                                 c = this.renderer.material.color;
                                 c.g = 0f;
                                 c.b = 1f;
                                 c.r = 0f;
                                 this.renderer.material.color = c;
                                 Debug.Log (collision.collider.name);
                         //}
                 }
                 //}
 
         foreach (ContactPoint contact in collision.contacts) {
             Debug.DrawRay(contact.point, contact.normal, Color.red,15f);
         }
 
     }