Did you ever find a solution to this problem? I'm having the same issue.
Hello! You must disable Anonymous authentication if you want to take advantage of Basic Authentication--you can't have both. Here's a link: Configure Basic Authentication (IIS 7)
I have checked our configuration, and all of our production websites have Anonymous authentication disabled with the exception of the default web site, which still has Anonymous enabled, as we wanted it to be publicly available.
If we enable Basic authentication on the default web site, our production sites require two logins to reach the respective sites. In the server log, we can see who has logged in to each site and the time stamp. Why is this not picked up in the editor tracking?