I ran into a lot of issues with personal images as well in my portfolio page through codepen. Github is the way to go in my opinion. I’m not sure what you mean when you say, “the original gets the images from a GitHub cloud.” When I was working through this project with codepen, I uploaded all my website images to a GitHub repository. The links worked for me then. An added bonus to doing it this way, is you can then migrate your codepen project to GitHub in the future.