hack or bug?

There are a couple areas where the height difference combined with the 3/4th view make for things that look wrong.

It's not a bug, and it's not a hack. It's just an issue with perspective.

http://prntscr.com/pv0wbh

it didn't latch onto him i think you missed it by literally 0.01

I am personally inclined to call it a bug. Riot's hitboxes have been known to be extremely wonky for a long time. A really good example of this is when very large champions try to clear nid traps/teemo shrooms with sweeper will randomly "walk" on it even though they are autoing it without moving. The main example i can think of is the hook through minion dilemma. Basically, champions have square/rectangle hitboxes that will overlap a minions hitbox if you're standing on top of it. Would personally claim that one as a bug. Riot definitely needs to review hitboxes lol