The issue on iOS is that the scroll events are going to your HTML Widget (iframe) and not the group, thus since the iframe is fully sized you’re just getting the elastic bounce back.
In theory you could choose “Ignore all pointer events” in the Actions inspector for the HTML Widget, but then that does not seem to have momentum scrolling.
It would probably be better to use the Inner HTML of a Rectangle element instead for your scroll view. This means you can’t use document.write, but you can use other methods to dynamically change contents if you need. Otherwise, you might be able to make your own
<iframe> element with the
scrolling="no" attribute, but that is just a guess as to if it works.