External link pop-up does not work on links inside of TabPanelWidget

I've got a custom Quick Tabs renderer plugin that uses the TabPanelWidget library (we selected it for both providing responsive tabs-to-accordions behavior and meeting Section 508 accessibility requirements).

It was discovered recently that the External Links pop-up notice is not triggered on links that are found inside of a Quick Tabs tabset that uses this renderer. I've set up an example page. The top accordion is made using the standard Quick Tabs renderer, while the bottom is using my custom renderer. The link to drupal.org will pop up the warning message in the first tabset, but not in the second.

The renderer is clearly not interfering with the pattern recognition, as the external icon is being added to the link.

I'm not seeing any javascript errors.

Anyone have any theories as to what's going on here?