When using Media Manager to archive media the key point to remember is that you need to select what you want to manage BEFORE selecting it from the menu. And, I always select what I want to Media Manage in the Browser, not the Timeline.
Understanding the Media Manager is critical to successfully recapturing media, whether for creating the highest quality final master, or for resurrecting an old project. But the Media Manager is not that intuitive. This article walks you through what you need to know for successfully recapturing your project.