I ran into that problem with a project not too long ago. It wasn't for something sticky though; a modal with video would dock itself to the bottom of the page on scroll to allow for content viewing but having the modal still visible.

On iPads that docking wouldn't happen until after the scroll had completed instead of at the start of the scroll. I'm not sure if this happens on the latest iOS versions or not though. But it was fun explaining to project managers what was going on during QA.