Hi Mr. Yuri, STL files contain only triangles. The MoI v4 SubD importer is only designed to import sub-d control cages from OBJ files, not dense non-subd structured triangle meshes.

So that's why the import is not working, it's not the right kind of data that the importer is meant to handle.

In general MoI is not designed to edit dense polygon mesh geometry, you would need to use a polygon editing program to do that kind of work not MoI.

- Michael