Ok, i think i got the problem, try to submit the project in FCC Page with the link of the codepen in full view, what i mean by that is you need to change the view of your project to Full Page View, try that and then tell us something !
Not sure when you mean. I had a problem with the URL I got from CodePen for my project. It was the origin ‘Fork Me’ page URL, not my work. I pasted that in. When I when back t the URL, it was the blank page. I lost all my work. I found out that you first have to click the fork button at the bottom right of the page to get the save button.
Then it will generate a unique URL for your page that you submit.