I noticed this behaviour recently and thought I’d share a potential workaround until I can find a way to solve it automatically.
Problem
With very very small meshes, you may find that they either disappear or never appears in the first place.
Solution
The reason is that Ragdoll filters out things it considers too small to worry about. You can disable this behaviour via this checkbox found under Advanced on the rMarker node of your control.
Check Zero Area Triangles
It comes at an infinitesimal performance cost, something you don’t have to worry about. The reason it exists is due to poor topology that can in rare circumstances cause Ragdoll to crash Maya, which is why this is a workaround and not a solution. For now, up till and including Ragdoll 2022.07.20.