To use this function, you must check off the 'team leader' button associated with your role. This will allow this function to work. This is done to limit the use of processes without a team leader's notice of how an event is being addressed. It stems from traditional incident response methodologies and management of resources. However, we recognize that there are many instances in which a team member may need to grab another process and keep moving forward. It only requires you to check the team leader box and you are good to go! Please read other FAQ regarding multiple team leaders for more information about email notifications and invitations to join events.
Visit this help article and scroll down to Roles, Step 1.