- My Sites contains all the sites that are added to you as a user.
- Sites contains all the sites in the network.
This can be confusing since you’re logged in as a superadmin and therefor have access to both but it simply means that the sites that are not showing up in the dropdown are not actually under your control (but you can still control them because you’re a SA).
Under Sites go to a specific site and go to the tab Users
Here you can add the users that have access to that site and if you add yourself to all of them, they will all show up under My Sites