Hi @davallree, thanks for reporting this. It appears to be a bug with how we host static site projects; we’ll have the team look into it!
In the meantime, a workaround is to convert your project to a Node project (copying the server.js and package.json files from the ~hello-express project is a good way to start). If you serve your HTML/CSS files yourself using something like express.static('your-file-directory'), you should start to see the Facebook graph debugger working.