EUREKA !!! My problem is solved.
I just changed the tag letter (name) of my WD 3 TB AV Internal Drive from ‘E’ to ‘M’ and now… it works !!! Who knows how, but with that astuteness, it works ! SmartWare is ‘happy’ and is now able to backup all my drives.
I hope that my odd solution will be useful to other members of WD Community.
Regards,
JDesjardins