I don't observe that on my system. Can you replicate that in test project?
Here is a test project:
I confirm that I see the problem too. However, I changed the cube collision shape to a cube instead of the mesh and the problem disappeared.
So my advice would be to file a bug, or maybe check if there not one already there, and put this project as an example of the issue.
Changing collision shape from mesh to cube cause a bit better than before, but not completely correct. Box shadow is still visible from side view.
But what about cone? It's much worse than the box! Can cone scales (in test project) cause this problem?