Darius v Garen immobilizing bug

As seen in the clip above: Garen (me) Q's to get out of Darius' E range. However that is unsuccessful. Darius then lands the E,W slow and Garen finishes the Q animation on Darius. The point to note here is that after Darius W till shortly after Garen's Q, Garen is moving towards the direction of the pull. Me being the player, I was scrambling to get to my turret. I was spam clicking the right side of the screen, but I had no control over my champion.

I have noticed this interaction in the past, but assumed it was me misclicking or doing something else wrong, but after the play above, i'm certain I had no control over my champion. Small instances like that, regardless of how the fight will turn out, is extremely frustrating.