Thank you Tim for your response. However, it seems that you didn’t try it yourself and made premature conclusion. Please see my screenshots. I added comments in them so you can see that it’s a bug.
When I move the L-shape box to the left (with sweep enabled), it does not collide with the box on the left. That small box also have a simple collision box and collision property set to “block all”.
I also tried to add more collision box in the mesh, but the result is the same. So how does a simple L-shape object cannot have a simple collision?
If I used auto-generate collision during mesh import, then it does not generate the desired collision shape.