Visual issues with Jhin's ultimate.

The visual bugs with Jhin's ultimate are caused by an intrinsic piece of your game's design: Spell particles are not shown outside of your screen area, and champion locations are not accurately shown outside of your screen area.

This leads to confusing cases where your target suddenly warps an inch across the screen because they used Flash but the game didn't show the Flash particles.

Outside of your screen area, the game takes a massive hit in accuracy and detail. That's just how the game is designed. It is not conducive to a spell like Jhin's ultimate. To fix these bugs, you'll probably have to do a massive amount of overhauling. I'm surprised the champion was released with an ult that plays so badly with the game's coding.