turret won't switch target

i don't know how to reproduce this bug, but it's extremely game breaking so i'm posting it here. i have the saved game files so if anyone wants to get a copy i can send it. I played a game today where top and jungle both towerdove me at top turret 1. teemo was tanking first, and he was getting hit by the turret, so i was able to kill him. before teemo died he ignited me, but after teemo died, leesin hit me a few times under turret, and the turret didn't switch to him, so he was able to get a bunch of free hits. would've gotten a double kill if it did.

contact me at my registered email on this account for file.