Nucleus sees internal storage but not the USB connected HHD

I need my Nucleus to see my external HHD to restore my database from a back up file. It does not show up in Settings/ storage/Folders/Add Folder.

Try Settings - Backups - Find Backups

Been there done that. It does not show up. Only Dropbox does.

What format is the HDD using? If it is NTFS, you may need to reconnect it to a Windows PC and then remove it safely before reconnecting it to your Nucleus.