smooth-scroll class on custom menu

I applied smooth-scroll class to circular menu About button. The jump link is to the h2 tag below the video. I also added this php code to my functions.php file:

add_filter( 'generate_smooth_scroll_duration', 'tu_smooth_scroll_duration' );
function tu_smooth_scroll_duration() {
    return 600; // milliseconds

Instead of scrolling, the page reloads and jumps to the link. I'm up to date on theme and GP premium (1.7.8). Also, I did check Smooth Scroll in Customize > General

Thanks,
Daniel