Sticky Class not working

with position sticky you should give top/bottom property too 

position: -webkit-sticky;

position: sticky;

top: 80px;

position sticky won't work if overflow property is given to parent (any parent)
second write below code to console.log and see where overflow property is coming
let parent = document.querySelector('.sticky').parentElement;

while (parent) {
    const hasOverflow = getComputedStyle(parent).overflow;
    if (hasOverflow !== 'visible') {
        console.log(hasOverflow, parent);
    }
    parent = parent.parentElement;
}

Mostly it's in dialog-off-canvas-main-canvas. locate and add below property to your js folder

if($('.sticky').length > 0){
$('.dialog-off-canvas-main-canvas').css('overflow', 'inherit')
}