Hi all!
I had the same problem as everyone else, and it I was able to get it working by changing DNS to 8.8.8.8.
Before that I tried opening MCT at least 20 times, with tips offered here: compatibility mode, disabling virus scan.. Some people here might say it's a coincidence that changing DNS helped, but I highly doubt that, since i tried so many times before..
Also, I see this problem has been around for over a month, and only now MS is starting to investigate it? wow...
Changing the DNS may very well have helped you. With that said though, changing the DNS to Google's is as much a solution as the others mentioned, meaning it may work for some, but most likely not for most who are having this issue. At least people are
finding some type of solution to kick it into gear, whatever it may be.
I still think it's a server problem, in that their servers aren't "seeing" people's setups the way they should, causing the tool to default.
And, no doubt. It certainly did take them a while to start investigating this.