Corrupted collision jitter bug/issue?

OK - so the bug(?) I am encountering is semi-broken collisions on some existing collisions

Video for more in-depth visual explanation: Unreal engine corrupted collision jitter bug? - YouTube

but to explain textually;

Many of my static meshes (with simple box collision) have an issue where the collision is unstable when a sphere is resting on it - a sphere will keep on “jittering” or performing small bounces.

A workaround is to remove the collision from the object - and re-add it - but finding more of these “problem static meshes” is making this more appealing - particularly after finding a (non-project) engine cube with the issue

I’ve uploaded a bugged cube, and a fixed cube here: Index of /stuff/buggycubes

any ideas on what the cause of the issue is, or how to fix?