Yasuo Q (Steel Tempest) not dealing damage or cast failing for no obvious reason

I was playing last night, 08/13/2016, with a group of friends on my Gold account. I had to fight a Mordekaiser top lane, and I wasn't looking forward to it. Well, one of my friends picked Kled and used his ult (CHAAAAAAARGE!!) on the enemy Mordekaiser, clearly a solid gank. Mordekaiser had no way of escaping so Kled and I (Yasuo) fought Mordekaiser. At the end of the fight, just before he was going to die, I went to cast my Q. Instead of him slicing forward, Yasuo stopped moving completely. The cast was slower, the animation didn't show Yasuo slicing, but it DID show the air around where the sword would have been if it did cast. There are WAY too many bugs on Yasuo as it is. I can deal with workarounds for nearly everything else, but this one is seemingly random and happens to me about four times a game. It's always when I need it the most and it's always after extended fights where I have to reliably land my skillshots to win. We still got the kill to Mordekaiser, but it resulted in a much sloppier gank that could've gone clean and pushed a tower. Instead, we had to back off because the bug extended the fight so that Mordekaiser could heal off of Kled. This started happening before Kled's release, but only slightly.