I’m seeing an empty body in the twitter widget’s iframe. This usually indicates that the widget iframe parent or some ancestor is moved in the DOM. Make sure that the widget source element (<a class="twitter-timeline...") is not moved after it has rendered. Browsers will destroy all contents of iframes if it is moved in the DOM after it has rendered.
There likely is some javascript on the page that is modifying the DOM around the widget iframe. It might be something async timing thing which is probably why it is working differently in different browsers.
