In the task and project drop-downs we will see the people depending on our project permissions.
If we have access to all the projects in the account, for example if our role is C-Level or Director, we will be able to see the names of all the people.
However, if our project permissions are reduced and we can only access those we are members of or someone in our team is a member of, we will only see people with whom we have at least one project in common.
Therefore, if we do not have access to all projects in the account, in order for us to see a person in a task or project dropdown, we must request internally to add that person as a member of at least one of our projects.