Turret targeting

So I just got done playing a game as gangplank vs Irelia. The game was filled with really strange things from beginning to end. For example, Irelia and me got into a fight. Her jungle, Vi joins in, while my jungle, Renekton comes. Irelia has teleport and flash. I flash away after Renekton stuns Irelia only to die to what seems like an ignite from Irelia. Renekton seen it as well and wasn't quite sure what to make of it. Anyways, fast forward to the next fight I get in with Irelia about 2 minute later. She literally dives under my turret and attacks me while the turret continues to focus a minion for two attacks before finally switching to her. She proceeds to kill me and walk off.

Earlier in the game as soon as I came into turret range, attacked Irelia with parrrley, and the turret would switch to me pretty quickly from a minion. Going back to Irelia turret diving me. I tp back in and a minute or two later a similar situation happens again. This time vi helps, and once again the turret proceeds to attack a minion while they're attacking me under it. Why does this happen? It happens every once in awhile, but it seemed like Irelia even noticed it because she kept diving me. This happened to me a few times today, but nothing as bad as the situation I just described. I wish LoL replay would work for me so I could show what happened. I don't mind getting outplayed, but when things like that happens, it's pretty frustrating. My ping and fps was fine. Felt no delay at all.

So I'm just wondering, does this happen to anyone else? I've seen older posts, but nothing recent about this. Also didn't know if I should of posted this in gameplay and balance or report a bug, so sorry if I posted it in the wrong section. P.S none of them had Ohmwrecker.