If CSS position: sticky; does not work as expected, there are various causes, but one possibility is to check if overflow: hidden; is not specified on the parent or ancestor element.
The property position: sticky; positions the element so that it follows scrolling within a specific area, but if overflow: hidden; is specified for the parent or ancestor element, the element may not behave as expected.
In this case, removing or changing the overflow: hidden; setting may allow position: sticky; to function properly.