@Niels_Oomen ah, so even as a super admin, there is a difference between every project you are a member of, every project you have access to, and every project in your entire organization.
The search that @Paul_Grobler recommended shows all projects for which the specified person is a member (you can see this on either the overview tab or by clicking the share button on the project to see the individuals).
If you use the search bar and enter no information (empty search), it will return all projects for which your account has access.
Even as a super admin, your account will not have access to private projects (or those in private teams) unless they have been explicitly shared with you. If you want to see all projects in your organization (including those private ones), the only way I know if is to create a service account [only for enterprise/enterprise+] and use the API to pull all projects in your organization.
I know this is not a simple answer; there is an existing thread requesting greater functionality for super admins; give that a vote if you’d like.