Dots are aligned along the contours of a square, but the four corner ones appear to be misaligned outward.pic.twitter.com/8GUJYqC6Et
You can add location information to your Tweets, such as your city or precise location, from the web and via third-party applications. You always have the option to delete your Tweet location history. Learn more
I think the less closed the angle is the better it works. Triangle doesn't work for me at all but starting from square I see the illusion. Octagon is probably the nest so far.
Twitter may be over capacity or experiencing a momentary hiccup. Try again or visit Twitter Status for more information.