I’m experiencing the same issue as well. http://tagpantry.com/wiki-test/
The code on that particular page is set as:
[rdp-wiki-embed url='https://en.wikipedia.org/wiki/United_States_Congress']
My website is running:
PHP version 7.3
WordPress version 5.1.1
All other plugins were temporarily disabled to try ad isolate the issue, and I did confirm the shortcode had ‘ (not the rich text version).
Your issue is the apostrophies (i.e. single quotes). You should use double quotes. Your shortcode should look as such:
[rdp-wiki-embed url="https://en.wikipedia.org/wiki/United_States_Congress"]
I do that and I use the wiki_links argument with overwrite. Doing that will not only embed that Wikipedia article on your page/post but if a user clicks on any link within the Wikipedia article, it’ll load that Wikipedia article on your site.
[rdp-wiki-embed url="https://en.wikipedia.org/wiki/United_States_Congress" wiki_links="overwrite"]
If not then any links they click on in the embedded Wikipedia article will open in a new window.
The page you reference is gone. Do you still want help with this?