I am having a problem with collisions not being detected between sphere collider and a mesh collider, but only when I run it on iOS. Everything works fine in the editor and in os x build. The setup is that a ball with rigid body should fall on an object with custom mesh collider, but instead it passes through. The ball is not moving very fast. Also on iOS the problem happens randomly, for most of the times there is no collision, but once every 10 or so restarts it works fine. Problem also seems to affect only mesh colliders with concave meshes and not convex ones (and I mean an actual shape not a collider setting). I've been trying the following things and none of them worked: Setting convex on a mesh collider. Attaching kinematic rigid body to mesh collider. Making mesh collider static. Setting "Continous" and "Continous Dynamic" collision detection. I double checked layers collision matrix. None colliders are triggers. Normals on my mesh are pointing out, I tried "Calculate" normals in import settings. In my test project one collider is very thick. Decreasing fixed time step and time scale in TimeManager. Decreasing Default Contract Offset in PhysicsManager. Increasing Solver Iterations and Solver Velocity Iterations PhysicsManager. Setting "Prebake collision meshes" in PlayerSettings. I created a simple test project that demonstrates the problem.