I have tried clicking on the link in the sidebar on the main page, as well as from the alert that Mysterious Melody has been reset. Everything else on the page (sidebars, ads, etc.) loads, but the center is completely blank. I have not had a problem joining before today. I'm using Google Chrome Version 53.0.2785.101.

Same here!

I just tried again and it worked.

There was an issue with the live server that has been fixed now. If you lost any items due to this, please file a ticket and a UA can assist you. Thank you for your patience!