Added option not appearing in dropdown until re-open

When the select2 dropdown is open, I add an option to my select element. The added option however does not appear until after I close and re-open the dropdown.

Select2 gets notified via the MutationObserver that a change has occurred on the underlying select element, and I see that Select2.prototype._syncSubtree() is called. Select2 however does not refresh the dropdown contents at that point.

Here is a fiddle:

Is this a bug or incorrect usage? Is there some other way for me to trigger Select2 to refresh the dropdown widget?

I have ready many, many posts about similar issues but have not been able to find a solution or a definitive answer about the expected behavior.