Horizontal Scroll - Position Sticky Not Working

I’m following a tutorial by Timothy Ricks on native horizontal scrolling. My issue lies in that my sticky element div won’t actually stick to it’s parent element.

The section in question is called ‘story-section’…it has 3 panels of content and the result I’m looking for is for the user to horizontally scroll up and down through the panels and once the panels have all been reached, the scroll returns to the native vertical flow.

Here is the read-only link: Webflow - Southfield Community Anti-Drug Coalition