Click on Menu Navigation animate to that Section

I have a menu, when I clicked on each nav, it used to animate to resume on that specific section.

Somehow, now it didn't do that anymore recently.

What should I check? I see nothing in my console.

Live : https://www.bunlongheng.com/

---

I used JS

This is the snippet

$('#main-menu').onePageNav({
    currentClass: "active",
    changeHash: false,
    scrollThreshold: 0.5,
    scrollSpeed: 750,
    filter: "",
    easing: "swing"
});

from Click on Menu Navigation animate to that Section