Teammates list and their assignments
The list of Teammates in your Front will show you your teammates' assignments that originated from a shared inbox. It will not show the emails from their private inbox. Click on their name underneath the Team section of your first pane to see their assigned conversations.
By default, you'll be able to see all open conversations assigned to this person. You can change this view by selecting the all filter at the top of the second pane.
Your teammate might have more assignments assigned to them that you can't see, because they might have access to different inboxes from you.
To customize which teammates show on your Teammates list, you can pin or unpin them from your workspace.