[Gameplay] If Leblanc's clone last hits a champion, Leblanc will not get any Dark Seal/Mejais stacks

Getting an enemy champion low and then, say, you use your R Q on said enemy and the clone gets sent out to mimic this spell and autos the champion after doing this, if the clone takes the kill, you will not get any Dark Seal or Mejai's Soulstealer stacks.

1. Purchase a Dark Seal or Mejai's Soulstealer as Leblanc
2. Get an enemy champion critically low
3. Use any ultimate empowered spell without hitting the target with said spell, do not use ultimate on itself
4. Hope the clone kills the champion

I was able to reproduce this 100% of the time, here are the two videos for clarity:

Bug in real game

Bug reproduced

Note my Dark Seal at the bottom