Hog3 fail to find fpspkg during 3.2.0 or 3.2.1 full install from disc burned from iso

I'm attempting to update my Hog3 consoles to 3.2.1. I downloaded the 3.2.1 iso and burned a disc in Disc Utility on my Mac, as I've done countless times for versions 3.1.9 and earlier.

When I choose "Software Upgrade" from the startup window, followed by "CDROM", the console returns and error "No fpspkg files found".

I also tried with version 3.2.0's iso file, and had the same result.

The desk is currently running 3.1.9 b 2946.

Thanks!