Unity Collaborate is a new service currently in Closed Beta. Here you can find some simple troubleshooting tips for the most common problems that may arise. Once you’ve been accepted to the Closed Beta, you will also be added to the Collaborate forum, where you can ask for further assistance.
If the information in Collab History appears to be out of date, right-click on the Collab History tab and select Reload for the latest available information.
If Collaborate seems to be stuck, try restarting Unity and/or verifying your internet connection.