Web Object: "Check URL or Internet Connection" error

When I include https://www.oregonhunger.org as a web object the preview action brings the above message.  But similar insertion of another site worked. As Adobe documentation says it could be because the first site is blocked to be rendered in an iframe.  But how do I verify and fix it.  We have a Drupal 7 based site that I do not see any setting or code that prevents it.  As a side note, when I use another plugin called "LiveSlides", same https://www.oregonhunger.org  site worked in the same powerpoint presentation.

Any pointers will be greatly appreciated.