Behaviors are only called the first time a view is loaded
Your "once()" function is called on an element with an ID. If your HTML is valid there can be only one such element in the DOM.

What happens with the once() function is that it adds a class to the element which marks it as processed. If the once() function is called again on the same element, it will do nothing. So looking at your code, it does indeed seem it will call the each() function just once on first loading, then never again.

It is right to use the once() function in this situation but you probably want to use a selector representing the children that can be dynamically created. I can't really advise what that should be without seeing the actual HTML.