In today's patch we've fixed one case that was causing the mini-map vision bug. For those not familiar with the bug, it's where an enemy champion icon appears on the edge of the fog of war for a split second in the wrong location. It quickly jumps to the correct location where the champion is actually standing (usually somewhere across the map). In the absolute worst case you would see the champion model and particles in the wrong location.
Our fix should lower the frequency of the issue significantly: we'd like to know if you guys feel like it's improved. Please post any feedback in this thread.