There have been some mysterious issues with the web simulation since the last update. For many people, some of the buildings are missing and falling off the face of the Earth is common. And I know the simulation won't load at all for others. Sorry about that. :-(
I probably should have said something about this sooner, but I honestly thought I'd fix the issue long before now. Not so much...
I think I have tracked down the issue and hope to have it fixed shortly. Unfortunately, everything looks perfect on my home computer so I don't know if the fixes worked until I test it out the next morning at work. It's not the most optimal troubleshooting arrangement. I'll get it though. I promise.
Thanks for you patience and the helpful feedback several of you have given me. :-)