Is the collision system just broken on BB3? I can't seem to get it to work and even some of the demo scenes have purposefully left out collisions that I also cannot seem to get working. For example on the Roll demo, you do not collide with the cones. Even if you enable physics on the cones, set them to static and add a collider, the ball just ignores them. I suspect this is because they are sub objects of the Helix which already has a collider. I can't see how any game is going to work though if you can't have collisions on children. I also tried adding nodes to the Actor object to detect collisions but they do not fire. This is beta 2, but I had the same problems with beta 1.
I've done a little more testing on this. Collisions do trigger on the cone, but if the ball is also touching the ground the cones do not divert the ball away from its current path. If you land on a cone, then it does trigger the collision.
I noticed the same thing (colliding with 2 adjacent aligned cubes "aka a wall"), the reaction was weird as if it collides with only 1 (corner), so I knew it ignores any collision after first collision test (which may be done from porting 2d collisions to 3d world collisions)