Quick + Self Cast bug

Previously when using quick + self cast, hovering your mouse over an ally with a spell such as Lee Sin or Braum's W wouldn't allow it to cast to that ally, and would instead only cast to your champion. Now the only thing that differentiates normal quick cast and quick + self cast is that if your mouse is not on anything and you use quick + self cast the ability self casts instead of just doing nothing. This makes quick + self cast much more clunky and pretty much useless in comparison to normal quick cast. I first noticed this bug a lot earlier in the season (maybe around 5.10?) and there was nothing mentioning it on Reddit or in any of the patch notes. I set a support ticket to Riot but it still hasn't been fixed many months later.