Why can't I find my backups on Google Drive?

The app shows the backup list, but on Google Drive there’s nothing.

This is due to the fact that the Google Drive App folder is hidden. It cannot be made visible by any means, as Google controls this behavior. Here are some more details: https://developers.google.com/drive/api/v3/appdata

In case you want to be able to access the backups, you can use Dropbox or SD-card based backups.