It’s a lower/upper case problem:
https://www.babylonjs.com/demos/productPage/ should be
The url inside the PG can easily be fixed, but there are also some paths in the GUI snippet itself… I fixed it programmatically:
It would probably be better to fix the snippet, but I don’t know if it’s possible.
The links can be fixed in the snippet as well with a new version: Babylon.js Gui Editor (babylonjs.com)