when a mesh is offsetted Solid using
_OffsetMesh command in Rhino 6 and the Flip all button is pressed once, the result is a mesh with inverted normals.
Regardless of the flip option usage, the preview is wrong. It shows a mesh with inverted normals but when the flip option is not used, it inverts the input mesh (if Delete input meshes is enabled) once completed. I wonder where is the logic ?