Targeted Abilties and Bushes

I have recently noticed while playing Pantheon or Annie, champions with a 600-625 range targeted damaging ability, that the damage seems to be completely negated by the enemy walking into a bush. It is most noticeable playing Pantheon, it is REALLY frustrating when you need to throw one more spear for the kill, but the enemy walks into a bush after you've thrown it and it does no damage and you don't end up getting the kill because of it.

The spell still goes on cooldown, the animation just shows it being thrown into the bush, when it goes into the bush you lose vision of your own spear and they walk out of the bush like nothing happened. I'm not sure about the mana cost, but I would assume it takes your mana, too. I know this is happening because I notice it does no damage, and the spear is supposed to crit if they are 15% HP or lower, and it happens on other champions such as Annie or Ryze with targeted single-target damaging abilities. The champions it has recently happened to are

-Gnar -Ryze -Garen -Morgana -Riven (she could have used her E, but there is no explanation to the other 4)

I don't hear anyone else complain about this, so Is this just a mechanic that I haven't found out about until now? I don't have recordings at the moment because lolreplay isn't updated for the new summoners rift, but I'll try to get a few clips if LoLPower actually records games it happens in.