Nothing displayed in "WPMU Dev"

Under "Site Admin" > "WPMU Dev" nothing is being displayed. I installed a mu-plugin, but still nothing displays in this section. I figure I did something wrong, so I deleted all files in the mu-plugins directory (except index.php & readme.txt) and tried again.

Exact steps were this:
- Downloaded the Rebranding WP plugin.
- Uploaded only the admin-footer-text.php file to the mu-plugins directory.
- Uploaded the update-notifications.php file to the mu-plugins directory (for the first time).
At this point "WPMU Dev" shows in the Site Admin" section for the first time after deleting all the files, but still nothing displays.

Image attached for reference.

Thanks in advance.