I believe that the issue is that the MAA server is configured to use SSL to serve pages securely (i.e. using https), but the image files are being sent insecurely (i.e. using http). Some browsers are more strict than others about viewing pages that have a combination of secure and insecure elements, and it looks like Chrome is refusing to load images in a secure page if the images are not sent securely.
I was able to reproduce this behaviour with Chrome, while Safari didn't complain.
I have reported the issue to the MAA. Hopefully they will be able to fix it.