[GAMEPLAY] Blitz Rocket Grab bug

So while playing in intermediate bots with my friend we noticed a bug. My friend was playing Blitzcrank and checking out the Piltover Customs skin I had mystery gifted him. When he launched his Rocket Grab and it connected with Zilean it failed to pull Zilean. All that happened was Zilean was rooted for about .25 seconds. It happened again later when he landed it on Caitlyn. Once again it failed to pull the target, and she was instead just snared for about .25 seconds. It only happened twice and the other Rocket Grabs he landed pulled the target they hit. I thought it was just a bot thing, but then I told my other friend about it. He explained that he was playing Blitzcrank in a normal game and when he was hitting his Rocket Grab at times the fist would go through the champion and they would not get pulled like they should have.