Being backed up in OneDrive should not stop Norton from backing them up. As long as they are stored locally on your system, they should be available for backup.
Are you storing your photos in a non-standard location on your hard drive? If so, you might have to manually add the folder(s) where you store them. This Norton Support article helps explain how. https://support.norton.com/sp/en/us/home/current/solutions/v20534334