[GAMEPLAY] Kha'Zix Q dealing no damage despite the animation going through

Kha'Zix has this bug for over a year now if I'm not mistaken in which whenever he uses his Q on a champion who can go invisible, flash out of vision or go into an unwarded bush his Q won't deal damage, even if the full animation goes through. This also happens whenever Kha'Zix casts Q on a target and dies very shortly (less than a half a second) after having cast it. The bug affects almost all of my Kha'Zix games and I play him quite often.

How to recreate said bug: Vision loss scenario:

1. Stand near a bush that you have no vision of while an enemy champion is also near that bush.
2. Have the enemy champion walk inside of the bush as you are casting your Q or have them flash into it.

The 2nd scenario is a bit more difficult to re-create due to timing but I'll try to explain it. Sudden death scenario:

1. Be on low health
2. Have one enemy champion (It doesn't matter who your target is and who is killing you, be it the same or different enemies.)
3. Cast Q and have them kill you while your Q is being cast, preferably in the fastest possible way for more accuracy with a high attack speed auto or some ability

Kha'Zix Q is a targeted ability but seems to be treated as a channeled one in this regard, which is quite unfair to him considering his main damage comes from the Q. He's an assassin, he relies on opportunities and having his main damage be so unreliable is just unfair to those who play him. It's cost me fights and games with how often it happens.