Kubuntu install from usb stick to usb-c ssd. grub install fails when not using 3rd party drivers

[John Minadeo]

 install also fails when using not using 3rd party but later in install.

ProblemType: Bug
DistroRelease: Ubuntu 20.10
Package: ubiquity 20.10.13 [modified: lib/partman/automatically_partition/question]
ProcVersionSignature: Ubuntu 5.8.0-25.26-generic 5.8.14
Uname: Linux 5.8.0-25-generic x86_64
ApportVersion: 2.20.11-0ubuntu50
Architecture: amd64
CasperMD5CheckResult: pass
CasperVersion: 1.455
CurrentDesktop: KDE
Date: Sun Apr 4 08:09:43 2021
InstallCmdLine: BOOT_IMAGE=/casper/vmlinuz file=/cdrom/preseed/kubuntu.seed maybe-ubiquity quiet splash ---
LiveMediaBuild: Kubuntu 20.10 "Groovy Gorilla" - Release amd64 (20201022)
RebootRequiredPkgs: linux-image-5.8.0-25-generic
SourcePackage: ubiquity
UpgradeStatus: No upgrade log present (probably fresh install)