If the .sh3f files you created are not visible in Windows explorer, how could you choose them in Sweet Home 3D to import them?
You probably saved them in a folder that is not the one you expected.
If you want, you can also [url=mailto:[email protected]]send me[/url] a .sh3f file to test it on my side, but as you can't find them, it's going to be difficult for you to attach one of them to an email!