Physics actor gets stuck

I have a blueprint class where the root component is a physics driven mesh, a ball. The scene is very simple, an empty room made up of boxes. A frame takes a stable 15 ms to render. The problem is that often the ball gets embedded in a wall or ceiling even at moderate speeds, ~40 km/h. (The ball weighs 1.7 Kg.)

Turning on CCD and physics substeps didn’t help.

One thing I forgot: physics calculations and the ball itself are constrained to the XZ plane.

Here is how the ball and the ceiling mesh are aligned (YZ cross section):


So the ball hits the box above right at the edge and that seems to be the problem. If the ball is moved a bit to the right then I can’t make it penetrate even with twice the speed.

Is this behaviour expected or a bug?