There is an issue with Google Calendar at this time whereby neither the sidebar nor the Calendar under the menu are populating events, future or past. This will likely be fixed soon but its a good time to mention that you can add this calendar directly on your phone.
There are a couple ways you can do this
1) If you have a gmail account, you can click on the +Google Calendar image at the bottom of the calendar. It will ask you to log into your gmail account, and then ask if you want to add this shared calendar to your own.
2) You can add a shared calendar to most smart phones.