cannot install ubuntu on luks btrfs uefi multiboot sda

[VS]

tried to follow this
https://teejeetech.in/2020/09/05/linux-multi-boot-with-refind/
https://teejeetech.medium.com/linux-multiboot-with-btrfs-luks-and-efi-part-2-7b0896c03cce

set sda as boot device, sda3 efi partition for boot and boom got this bug. My root is btrfs. I already have refind and manjaro installed on existing luks btrfs root filesystem as per the links i followed.

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: ubiquity 18.04.14.15
ProcVersionSignature: Ubuntu 5.4.0-42.46~18.04.1-generic 5.4.44
Uname: Linux 5.4.0-42-generic x86_64
ApportVersion: 2.20.9-0ubuntu7.16
Architecture: amd64
CasperVersion: 1.394.3
Date: Wed Jan 20 18:35:10 2021
InstallCmdLine: BOOT_IMAGE=/casper/vmlinuz file=/cdrom/preseed/ubuntu.seed boot=casper quiet splash ---
LiveMediaBuild: Ubuntu 18.04.5 LTS "Bionic Beaver" - Release amd64 (20200806.1)
SourcePackage: grub-installer
UpgradeStatus: No upgrade log present (probably fresh install)

[VS (ryzengrind)]

Did some digging, this seems to be the error. But After I checked UEFI version now I am more confused.
Jan 20 23:35:07 ubuntu /plugininstall.py: File "/usr/share/ubiquity/plugininstall.py", line 929, in configure_bootloader
Jan 20 23:35:07 ubuntu /plugininstall.py: "GrubInstaller failed with code %d" % ret)
Jan 20 23:35:07 ubuntu /plugininstall.py: ubiquity.install_misc.InstallStepError: GrubInstaller failed with code 1
Jan 20 23:35:07 ubuntu /plugininstall.py:
Jan 20 23:35:08 ubuntu partman: No matching physical volumes found
Jan 20 23:35:08 ubuntu partman: Reading volume groups from cache.

UEFI/BIOS CHECKER
ubuntu@ubuntu:/mnt/btrfs$ [ -d /sys/firmware/efi ] && echo UEFI || echo BIOS
UEFI

So I am confused why installer failed when live USB is booting from grubx64.efi Refind and installation is done on ssd with luks, btrfs, running pre-existing manjaro os and filesystem. Any help would be appreciated.