Jungle Monsters Freezing With Master Yi

I just got done playing an unranked match as Master Yi in the Jungle. I noticed while clearing blue buff and the wolves on bot side of the rift that when I used my Q on them, their models froze, however I was still taking damage. I didn't know what was going on the first time at blue, but at the wolves, I did miss an auto, e than q before the monsters froze. I didn't have time to test any other camps during the game, but it wouldn't surprise me if this happened to all camps. I wasn't recording the match so I have no video proof, but since I was able to pull it off twice in game I think it should be easy to replicate.