Hi Morten

Just because you are in the db_owner role, does NOT mean you own the
database (as your subject line suggests). You are still just a user, but you
have a greater set of rights than most users. Information about which users
are in the db_owner role is only stored INSIDE the database, and without the
VIEW ANY DATABASE permission, SQL Server will not look inside the database
to see if you happen to be listed as one of the users in db_owner role.

If you want to see databases without VIEW ANY DATABASE permission, you have
to be the real owner, which is stored in sys.databases in the master
database. SQL Server can see that info without going to the database itself.