When doing a review of the site, I can see one issue with the z-index on the navbars
navbar class in navbar black has z-index of 10
navbar white menu has a z-index of 5.
The issue is caused because the navbar white has a lower z-index than the navbar class and the navbar white menu is below the original menu and links are not clickable.
To fix this, set the navbar white menu class to display none and opacity 0%. Next update the interaction to add a trigger, to make the navbar whitemenu display block and then opacity 100% on scroll into view, and display none and opacity 0% on scroll out of view.
I have made a quick video to describe this.
I hope this helps, if not, let me know and I am happy to check further: Cheers, Dave