Do you have a pst or an archive that has tasks and flagged mail it, but the tasks and flagged mail don’t show up on the To-Do Bar? Here’s how you can make it work!
Right click on the name of your archive, (in the picture below, the archive is named “StuffForToDoBar”), and select ‘Properties for “<name of your archive>...”’
In the dialog that appears, check the box next to “Display reminders and tasks from this folder in the To-Do Bar”
Viola! Tasks and flagged mail from your archive in the To-Do Bar!