Hi ibowden,
Using the terminal for this task is quite easy to learn. To summarize what Usman said, the generated backup files are placed in /home/yourdomain/backup/ but need to be moved to /home/backup/ in order for Cyberpanel to recognize them.
Once in the terminal, gain root privileges sudo su and navigate to the home directory cd /home/
From there you can check to see if the backup folder exists by typing ls if you see backup then skip this next step. To create the backup folder type mkdir backup. Now that your backup folder is created you will need to move the backup file.
Navigate to the sites backup location by typing cd /home/yourdomain/backup/. From there you should be able to type ls again to view the backup file. It will start with backup and end with .tar.gz
To move the file type mv backup-yourdomain.tar.gz /home/backup/.
That should complete the process. In the future you will not need to create the /home/backup/ but rather just follow the same directions to move any other backups.