Completely invisible stealth

[Phinyx]

So i was playing in arena and noticed that whenever sin or summoner enters stealth, they are completely invisible, I mean completely. Before I could see some contours/misshaped light if you look good enough, but now its just thin air, it's like hes not there. I don't know is it a bug or my settings ( I tested all effect settings but no change). If anyone else having same issue or know how to solve it, reply.

[Tsumetai]

Most likely to be a hack, if not in the patch notes.