[GAMEPLAY] Xin Zhao can not be terrified when using ultimate?

I played as Fiddlesticks and found a strange behaviour, when while xin used his ultimate i terrified him, but after his ultimate ended (about 0,2 sec later) he could still hit me. I recorded the full match and uploaded it to youtube, so you can check it out in more depth.

Steps to reproduce: 1, xin should jump to fiddle with his "Audacious Charge" skill using his "Three Talon Strike" and "Challenge" skills (maybe not important) 2, use his ultimate immidiately when arriving on fiddle sticks 3, fiddle should try to terrify him while xin casting his ult

It is a very rare issue because its hard to time it that accurately.

Link to my video: Link

happened 2 times: 14:30 and 19:30 in the video. (If you use the youtube's speed option to view it at 0.5 or 0.25 speed it can be seen clearly)