Hi Jeremy,
We’re having the same issue, but we double checked that our URL is correct. We followed the directions here on our Dreamhost server, but when we actually tried running our experiment it says preloading for a long time and then an empty box appeared where our image should be. Here’s the demo experiment, where we tried replacing the logo with an image from our server.
https://expt.pcibex.net/ibexexps/backColor/backColor/experiment.html
Any ideas on what’s going on? Appreciate the help!