I have seen this as well on 2 recent installs. the one today is running 3.5.1 wordpress pointing at test server.
You can create a single meeting.
But after creating the single meeting the list of meetings is blank.
From the home page widget you can join fine. After the meeting, could go to wp-admin login to settings page, and you see the meeting, if has JOIN, END and DELETE option now When you click JOIN again it returns a blank settings page.
Logged back in wp-admin, can see it fine, and I could END it, but not join.
Will troubleshoot some more.