My Directory is back. After many hours of trial and error, the Directory reappeared after I deactivated and reactivated the UM 2.04 plugin.
I am not sure that is the entire solution. I first rolled back to UM 1.3.88. Not only was the Directory still blank, but restricted menu items and private areas became visible to everyone. I deleted the UM Captcha plugin and updated to UM 2.04 again. The menus that broke during the rollback, remained broken. I restored the entire database from a backup. I restored to the state after the first UM 2.04 update. Directory was still blank.
After all of the above and more, I deactivated and reactivated the plugin and the Directory reappeared. Perhaps I should have tried that first?
I am not going to mark this thread as “resolved” … yet … even though the Directory appears to be fixed. There are still issues. New member registrations are set for pending review, but that isn’t working. New member registrations are automatically registered for WP (even though we have unticked the WP setting “Anyone can register”). New registrations are not assigned as members pending review. Email notifications are being sent out with raw code, or the wrong emails are sent. Other users are also reporting these issues after update to UM 2.04.