So last week an announcement came out where Outlook Web App had been hacked so I had to change my password. Apparently when you setup your ScheduleOnce Integration to use 365 (which I gotta say is one of the coolest integrations!), it quits working if you change your password.
In ScheduleOnce, simply Disconnect and Reconnect the calendar (under Integrations). 🙂
You can read more about the Outlook Web App Hack here: http://news.softpedia.com/news/hackers-breach-microsoft-owa-server-steal-11-000-user-passwords-493762.shtml