Jungle gameplay error

Occasionally the jungle monsters will stop doing their attack animation but will still be able to do damage. So far I have only noticed it on the red side and it usually happens whenever I use Master Yi's alpha strike on them. It isn't consistent and the larger monsters will also move in a jerky, robotic way while the smaller ones will not move at all(unless I re-position myself from the camp.) I was not able to re-create what happened in a private game of bots but it has happened to me more than once in normal matches on summoners rift. It may have happened to me while using Xin, but I wasn't paying attention for the issue that game.