Have reviewed again since you've updated. It's due to your template applying the below CSS.
IN: /media/gantry5/assets/css/bootstrap-gantry.css
ON: Line 4616
Code:
.media, .media-body {
overflow: hidden;
*overflow: visible;
zoom: 1;
}
Hiding the overflow prevents the dropdown from displaying. Looks like that's default behavior for Bootstrap 2.3.2. Have added a bug ticket to review adding a workaround.
forge.joomlapolis.com/issues/7654
Will try to have a fix available shortly.