There are some issues around access tokens in Manage where the experience varies based on the version. In the earlier 9.1 builds you'd be randomly redirected to the start center if you used multiple tabs and one of the tabs hit the Manage session timeout (defaults to 30). In 9.0 you'd lose the ability to access the profile/logout and such for the bug. There have been some changes IBM has made but there are still open issues with the access token management from Manage. It significantly improved the user experience adjusting the web.xml to increase the idle timeout. For 9.0, we also told people to navigate to the home URL, and it would re-establish their session.
A few people that have used Operational dashboard heavily had issues where the local storage filled for the site. In that scenario you'd navigate to the dashboard or some of the other role-based applications and it'd be blank. We weren't able to pinpoint exactly what the bug was and how to recreate, so we haven't opened a support ticket on that.