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. My concern is that this slight difference is what is causing the problem when working with many compound colliders consisting of many primitive colliders.