Jarvan IV not showing Martial Cadence proc auto attack.

I noticed this last night when playing a game as him, as I auto attacked Gromp the Martial Cadence proc animation didn't go through, he just stood there, the damage went through and it did effect the target. I also noticed that randomly an auto attack animation wouldn't happen.

I know it's not a huge thing, but it's actually frustrating to see and can affect gameplay to some extent.