Here is my calendar http://www.screencast.com/t/CDpw8un2T . Notice how blissfully empty July 10 is. That’s because I removed the instances of the recurring events from my calendar as those meetings were all cancelled.
Here’s my forecast view http://www.screencast.com/t/VyJMzBy2XyK . Note that it’s NOT empty despite syncing, removing then re-adding the calendar, changing my security settings, syncing the calendar in the calendar app, etc.
I have many calendars in my list and I’m definitely not subscribed to all of them since many are redundant like the various sources of US holidays.
I just tested this and it looks like the issue is limited to recurring events to which I’ve been invited. I created a recurring event of my own and when I deleted one or more instances of the recurring event then synced in my calendar I was able to see the correct number of events in the Forecast perspective. I tried this with iCloud calendar, Google calendar and Google Apps calendar and the results were consistent.
Found a fix through someone at support. It has to do with declined events. Find the “show declined events” button, enable it, and make sure the events are deleted.