Fixed transformation of the hollowed mesh to be used at frontend

Common gizmos data update is called from GLGizmoManager

src/slic3r/GUI/Gizmos/GLGizmoBase.hpp

@@ -215,6 +215,7 @@ public:
 
 private:
     const TriangleMesh* m_old_mesh;
+    TriangleMesh m_backend_mesh_transformed;
 };
 
 } // namespace GUI