This has been a problem with Outlook Today since the start. The use of Outlook Today is flawed since the Tasks section of Outlook Today will only show an actual Outlook Task. It will not showed flagged emails that show up as Tasks in the To-Do view. The only way to see flagged emails in Outlook Today is to open the To-Do window showing flagged emails (ironically as non-Task tasks). I've seen people asking about this repeatedly in other forums and no one seems to understand what is really being asked. A great enhancement and feature would be to simply provide an option to allow Outlook Today's Task section to display flagged emails, instead of adding another window pane (the To-Do window pane) to the right of Outlook Today, which reduces the effectiveness of Outlook Today's snapshot of "today." The screenshot below is the only way to show flagged emails in Outlook Today. What a waste of screen space. Why not just show the flagged emails under the Outlook Today Tasks section (the left highlight)?
I've attached a screenshot to eliminate confusion.