Invisible Kai'Sa

So I was playing a Legend of the Poro King game. You know, usual stuff. Then all of a sudden, I looked at Kai'Sa, and she was invisible. You could only, very faintly, see her outline. Apparently this was only on some people's screens, as my teammate Ahri said that she was invisible for her too, while Kai'Sa herself said that she was fine on her screen. I didn't pay attention to what could have caused this.

Here's a screenshot of the invisible Kai'Sa https://gyazo.com/febd5dd52d607f33f101f2182f219087 Here is another screenshot of the invisible Kai'Sa (albeit a bit worse) https://gyazo.com/4c5cb6de1e7b5dd965786b3176372196

Here is a screenshot of the game, confirming it was Kai'Sa https://gyazo.com/146151cccdbdf9276e8d8a4d8c9a7ddc

I wonder what could have caused this.