CodePen JSONp problems Wiki viewer

I was just testing my Wikiviewer in codepen and it is not working.
There seems to be a problem in the JSONp in Code pen. Is this a known Issue in Code pen?
The page works fine in my live server in Atom.
Also I have it live in plugin section in a app building platform.

Here is my project in code pen:

Also here is a working version live: https://testapp2018jay.goodbarber.com/myplugin

Should I be using a CORS method instead of JSONp for this project?
Any help or feedback of why this may not be working in code pen will be greatly appreciated.

Thank you,

@camperextraordinaire
Thank you so much for your help. You were spot on.