Hi Tony, yup that is a bug, thanks for reporting it. I've got it fixed up now for the next release.

There is a new display mesh mechanism which is meant to detect when a face has not been changed between operations, and just copy the face's display mesh over in that case instead of calculating a completely new mesh.

That's not fully working yet but once it is it should help to speed up operations that only affect a small area of a solid, the idea is to only calculate a new mesh for altered faces.

But this mechanism is kicking in accidentally in this case, when you actually want the mesh to be recalculated to match the new settings.

- Michael