Compound colliders are acting strangely

Are you building it through code? That sometimes breaks physics, often making it look feathery. You just have to add a line to "kick" it.

Yes I am. How do I kick it? Do I add a bit force? If so how much?

So I did an experiment where I set up a three cubes with a box collider each under a single transform with a rigidbody (compound collider) and a single cube scaled to have the same shape with a single collider and a rigidbody (normal box collider), and the same problem appears to be present in this experiment. So it is not caused by scripting.

Couldn't duplicate that. 4 Unity cubes w/box collider. Child to empty with rigidbody. Tried two ways, adding the RB to the parent before/after childing the cubes. Either way it seemed to fall/bounce just fine.

The difference is subtle. It appears to me that the compound collider seems lighter and is more likely to slide, but I'm not entirely sure. $$anonymous$$y concern is that this slight difference is what is causing the problem when working with many compound colliders consisting of many primitive colliders.