Modal and Sortable List not working well together


I have a sortable list (<ion-list ... show-reorder="true">) which is shown in a Modal (Codepen: Sortable ion-list in Modal scrolling weirdness)

The problem is that the automatic scrolling on the list while dragging an item missbehaves (it scrolls too fast or not at all / scrolling starts at “random” positions).

To reproduced this behaviour simply try to drag item #3 to position 40 and you will see.

Does anybody know if this is the intended behaviour or if it´s a bug?
Is there a guide on how to properly extend or modify ionic “widgets”?

Thank you.