Bug on autoattack-reset abilities (Gameplay)

Vi is my main jungler and i noticed something really weird lately. When you use her E immediately after a basic attack, it occasionally fails to go off, doesn't play the animation, or just makes her stand there and do nothing. I played Darius today too for the first time since the update, and noticed the identical issue with his W. Both are autoattack resets, and both have the same effect. Darius was nearly every time I used the ability, Vi is sporadic, but it seems to be the quicker i try to use it after the attack the more likely it is to occur. While playing Darius it had the effect of essentially locking him in place unable to move or attack several times, Vi's will make her unable to attack but still can move. If it's relevant, I was using the Woad King Darius skin and Officer Vi. I noticed the bug across multiple games for several days in Vi's case, and just in the one game I played as Darius. Not sure if it's me somehow or an actual bug, but it can get pretty bad in certain instances.