Akali needs to be seeable under turret if she hits you with an ability.

I don't care if she is initially invisible when going under turret, but she should not be able to RE-ENTER stealth and remain hidden. If she cannot position her shroud to touch on an area outside of turret range, she should not be allowed to freely. Her current state makes turret diving exceptionally easy for her, and renders your turret absolutely useless, especially since she can hard push the lane with Q since the ability passes through minions.