If you created a file or directory named either "internal" or "share" you won't be able to see it or delete it. This problem is easily fixed but you need SSH access to your WD.
SSH into your MyBook and goto /var/oxsemi/ directory.
Edit smb.conf file. In there you'll find a line that says:
veto files = /shares/internal/.senvidData/ /shares/internal/lost+found/
Change this into:
veto files = /.senvidData*/lost+found*/
Save the file and restart Samba using this command
killall -HUP smbd
Alternatively you can restart MyBook.