I have a blue box update as well.
I tried the obvious approach that seems to have only worked for giessen, but not for all of the regulars on this thread.
Well, it didn't work for me either, but I didn't have time to do more playing as I had to hit the road. So, I left it in there.
While on the road, I played around a bit with the system, and discovered that when I canceled a route, guess what? The blue boxes disappeared! So, the initial drawing of the boxes must be coming from somewhere else. But then once navigating, then canceling, they go away.
When I get a little more time with the car (tomorrow), I'll play a little more. I do like this straightforward approach a little better than the more complicated approach that skicrave and stephanie have been thinking most recently, if I can get it to fully work.