Tryndamere Ultimate ability is not working correctly.

So yesterday it was lunal revel, and 's skin Warring Kindoms was purshaseable. I was hyped, i bought the skin and played this bad ass top laner, remebering my season 4 climb from bronze to silver in 4 days. I was facing , everything was going normally until i got my level six. At this point, my jungler came top to gank, so i jumped on vladimir, slowed him, started to a-a with my jungler. HE was about to be dead, but he used his pool, and when he came back from it i ulted cause i knew he could kill me with E-Q. Somehow, i heard the roar of when he falls in ultimate stance, it felt on cd, but his damage passed trought my invulnerability and killed me. I immediately understood it was bugged, but i was wondering it might just happens with this skin i just bought....

So here's the point. I disconnect from my main, go on my smurf account, get into a normal game and play . Someone picks in my game. I warn him that there is probably a bug with his ultimate, and to not take his warring kindoms skin. So he takes classic skin, we got into the game, about 35 minutes in the game trynd get caught. He flash ulted immediately toward the ennemy, starts to a-a her, she flash away and Zap! him. dies again. In his ult AGAIN.

i would like to know if it happened to any of you, because is a really frustrating champion, that is to say that his ultimate is difficult to time, be as low as possible to have maximum efficiency from it, but not to much cause there's a 0.5 second delay on his ult... When you die as you press R, it is furstrating,I think Tryndamere has a high skill cap cause of that.. Whatever, I mean, it was really more frustrating to know that you ulted correctly, but that somehow you still get killed....

i would like to have your thoughts, at worst you could play him 2-3 games and see if it happens to you.

Thanks!!!!