Hi Jeremey,
Thank you for sharing me the URL! I tried your experiments two times, and now I am able to run your experiment and my own without problem. I found that my browser disabled the third party cookies when I visit pcibex.net domain. Once enabled, the experiments successfully run!
The cookie permission button on the browser is small and hard to find sometimes. If PCIbex could present a popup to allow the use of third party cookies, it would be very useful. I would be grateful if you consider the implementation of this kind of functionality.