Twice now I've had over a million gold (and hovering just over currently) and I still have not correctly received the Millionaire achievement. Yesterday when one of my store listings sold and I shot up to around three million gold, I got the achievement message pop up and the top bar showed I gained the 200 points, but the achievement page listed my points as if I had not and the icon was still in the unearned section. Today, the top bar is back down to match the achievement page and I still do not have the achievement.