We are not able to reproduce this behavior with Sitefinity 3.7 versions. You can give a try to our demo website http://demo.sitefinity.com
and try to reproduce the problem there. If you manage to do it, please send us the exact steps you have followed ( make sure that you have additional url that redirects to the generated one as shown on the screenshot you sent us).
If the problem persists we will need credentials to your website backend, so we could see what is going wrong. Actually when Redirect to default
is checked this means that your request will be redirected to the default url generated by Sitefinity. In our case you should also get 404 error when access this url, since a redirect is made.
Let us know how it goes.
the Telerik team