It might be the UI design causing confusion, or being plain wrong.
What does this say?
USE YourDatabaseName;
GO
SELECT sp.name
FROM sys.database_principals dp
JOIN sys.server_principals sp ON dp.principal_id = sp.principal_id
WHERE dp.name = 'dbo';
GO
There are no special teachers of virtue, because virtue is taught by the whole community.
--Plato