Why mesh colliders in Unity 5 does not always detect collision with ground?
Sample setup: A plane, a mesh with Rigidbody and collider (mesh, box or capsule) not set to be a trigger, and positioned at some height. If height is greater than 1 meter, the object falls through the plane, but if height is less than a meter, sometimes it falls and sometimes it doesn’t. Same setup works 100% in Unity 4. Using a 1 meter thick cube as ground solves the issue, but doesn’t seem optimal as 5 faces of the cube will remain unseen by the player… This also means that you’ll have to replace all planes with solids (walls, doors, windows and maybe even other GameObjects) just to ensure things don’t get teleported.