The problem was the height defined for the body.

The body height was defined as height: 100%, with this parameters the scroll event does not work, even if the page is scrollable.

The problem is that when this element is constrained to exactly 100% height of the viewport, it can affect:

• How scrolling works on the page
• How fixed-position elements (like the button) interact with the scrolling behavior
• When scroll events are triggered