bug? Program reports non manifolds and disconnected shells

My CAD program (Rhino) reports object as closed solid no naked|non-manifold edges, yet bumpmesh reports it as having some non manifold and "disconnected shells"

It prints fine either way if I ignore it.

Seems like maybe a glitch or something?

<img width="388" height="120" alt="Image" src="https://github.com/user-attachments/assets/3520aa42-665e-49ee-9b69-12dbe64d4920" />