My conclusion is:
1: Not a Debian Live-Build issue
2: Not a Debian Installer issue
3: The issue comes from the --architectures amd64 \ not being in the file noted in this post forum.linuxcnc.org/9-installing-linuxcnc...-iso?start=10#336354 (post above).
4: It has been an "Us Issue".
If anyone is able to confirm that the ISO performs as I have found, no rapsi-firmware found in a Live Session or after running the Installer on the ISO, I would be very grateful.