I don't record my games and I'd need to see it in slow motion and really take a good look without being distracted elsewhere to be sure, but in my games sometimes it does feel like towers aren't reacting to dives fast enough.
That said, what could simply be happening is that the tower has already started its attack animation on a minion right as the diving champion attacks, meaning that the tower needs to finish this animation before it can change targets to the champion. If the champion then exits the tower's range before it gets far enough in its attack animation towards the champion, it fails to attack the champion as well. To be specific, try playing against bots and diving them under a tower. If you dive as a tower is about to attack a minion it takes a rather long time to target you as it needs to wait a full attack, however if you dive just a little earlier you take an attack almost instantly.
Honestly, I'm torn on whether this is a necessary "skill" in league. At high levels of play, I'm sure players determine when to dive based on when the tower is hitting minions to minimize damage taken. However at most levels of play it's probably irrelevant and completely luck based - so the tower gaining an auto-attack reset when a champion is targeted under tower may make things more fair?
Really not sure on this though. And not sure if there is a targeting bug regarding towers right now.
