There are sections of the minimap that are visible to both sides, a section between the first and second towers on the red side, directly behind the gromp. I first noticed this when i was playing miss fortune and I was walking back and forth looking at her new walking cycle/animation, then someone on the enemy team said in all-chat that they could see me, at first I thought he/she was just saying that for whatever reason and I didn't pay any attention to it. Then I played another match later today, I looked at the minimap and noticed that I could see minions walking down the lane DIRECTLY behind gromp and then I saw the enemy tahm kench walking to lane too, it was then when I realized that that's what he/she was talking about. Not a game breaking bug but it's still there.
tl;dr there's a section of the minimap behind gromp that you can see enemies on red side