We are bringing a migrated 2010 farm into production and have run into an odd situation with one of our first departments to go live on 2010. We used the attach and upgrade method to upgrade from Sharepoint 2007. This particular user is the site collection administrator and has full rights through the web app contains his (and only his) site collection and sites. Though his rights seem to be intact (checking his rights shows the right answers) his user name is not visible in any of the groups he is in. In the other web applications I can add him to a group and he shows up as he should. In any group within his web app, if he is added to a group, his username never shows up; his membership in the group is represented when I check his rights. No amount of searching has revealed a similar problem being discussed.