Fake Fog of War

This is in my opinion game breaking. Sometimes Summoners rift and the mini map will remove the fog of war from patches in lanes yet still have the effect of fog of war. There is no vision there for these spots to be lightened up like they are. When you are standing near the entrance of the spot they map is still lit up but you can't see anything til something walks into your vision. This results in minions that were walking in this spot just appear from out of nowhere. You can't see champions til they are right up on you. It has gotten me killed a few times already. It doesn't happen every game. The main trigger is when I dc or this other visual bug occurs in which stuff like summoner aeri flicker in to separate lines when returning to either character. You have to close the client for it to get fixed but when you come back the map does the bug I'm describing. This is seriously ruining some of my games because i can't look at the map for information.