ES2.1 My Events show all attendees under the "Friends in Event" widget

The site URL I've provided is just one example of an event on my site.

Since going to ES2.1 today I notice that whether you are logged in or not, all the event attendees show up under the 'Friends in Event' sidebar widget.

I don't see this same issue on the ES demo site, so maybe unique to my site, or something to do with upgrading...

Any ideas?!