Comment 2 for bug 1813126

I've confirmed this with a new 19.04 install, and it's not just the d-r-u process.

In a manually configured system with:

sda3 -> LUKS_BOOT > /boot/
sda4 -> sda4_crypt -> LVM -> /dev/mapper/ubuntu-rootfs -> /

# grep -rn GRUB_ENABLE_CRYPTODISK /etc/default/grub /etc/grub.d/ /usr/lib/grub/ /usr/sbin/grub* /usr/share/grub/
/etc/default/grub:33:GRUB_ENABLE_CRYPTODISK=y
Binary file /usr/sbin/grub-install matches
/usr/sbin/grub-mkconfig:245: GRUB_ENABLE_CRYPTODISK \
/usr/share/grub/grub-mkconfig_lib:77: if [ x$GRUB_ENABLE_CRYPTODISK = xy ]; then
/usr/share/grub/grub-mkconfig_lib:162: if [ x$GRUB_ENABLE_CRYPTODISK = xy ]; then

# grub-install /dev/sda
# update-grub

both fail to add the luks and crypto modules. Core image doesn't get them:

grub-install: info: grub-mkimage --directory '/usr/lib/grub/i386-pc' --prefix '/grub' --output '/boot/grub/i386-pc/core.img' --format 'i386-pc' --compression 'auto' --config '/boot/grub/i386-pc/load.cfg' 'ext2' 'biosdisk' 'search_fs_uuid'

and nor does /boot/grub/grub.cfg:

...
menuentry 'Ubuntu' --class ubuntu --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-simple-a0f21372-a236-4e33-9bfa-9921ca89d5b7' {
        recordfail
        load_video
        gfxmode $linux_gfx_mode
        insmod gzio
        if [ x$grub_platform = xxen ]; then insmod xzio; insmod lzopio; fi
        insmod ext2
        if [ x$feature_platform_search_hint = xy ]; then
          search --no-floppy --fs-uuid --set=root 997c6523-62d6-4274-bf2b-3fa0bef7f181
        else
          search --no-floppy --fs-uuid --set=root 997c6523-62d6-4274-bf2b-3fa0bef7f181
        fi
        linux /vmlinuz-5.0.0-16-generic root=/dev/mapper/ubuntu-rootfs ro quiet splash $vt_handoff
        initrd /initrd.img-5.0.0-16-generic
}
...