Unable to click minions after a while

I have no idea what causes it at all. One moment I'm clicking minions just fine. Then all of a sudden, I'll be absolutely unable to click them at all. If I try to click them, the cursor will just make the arrow simple and the champion will just walk into the minions instead. It happened once during an SR game when I was playing Wukong and another game during ARAM when I was playing Urgot.