Missing media files after iMovie 10 "Update Projects and Events"

The first time I fire up iMovie 10, it asks, “Do you want to update your projects and events?” I click “Update”. A progress bar is displayed while the update is in progress. Event folders are created in the new iMove Library, but the folders are not populated with the actual media files from the iMovie Events folder. The iMovie Events folder is from a TM backup. Is it possible the folder is corrupt (i.e. missing/corrupt CurrentVersion.flexolibrary, CurrentVersion.imovieevent files)?

I’ve tried “Update Later” and a manual update from “File -> Update Projects and Events”; same outcome.