Comment 7 for bug 1915579

I also have this problem (with a LUKS & LVM). As a workaround, I did:

1) boot into live CD, start a terminal and do everything as root (sudo -i)
2) open the encrypted LUKS partition: cryptsetup luksOpen /dev/nvme0n1p3 nvme0n1p3_crypt

Note that the name (in my case "nvme0n1p3_crypt") must match the name that is in the etc/crypttab . Otherwise the later generated initramfs will not work correctly.
3) vgscan && vgchange -ay vgubuntu
4) mount /dev/vgubuntu/root /mnt
5) mount /dev/nvme0n1p2 /mnt/boot # this is my /boot partition
6) mount --bind /dev /mnt/dev && mount --bind /sys /mnt/sys && mount --bind /proc /mnt/proc
7) chroot /mnt
8) chmod 755 /usr/share/initramfs-tools/hooks/lvm2
9) update-initramfs -u