I've looking for hours why my own scripts
placed in "usr/share/initramfs-tools/scripts/live-bottom/"
with chroot-hooks, chroot-includes, good perms, echoing in debug files, etc... didn't run.
I was making update-initramfs, my scripts appeared in the live system, but was not executed...
the problem was the script's name, with the ext .sh (e.g. 05foo.sh), wich is rejected by mkinitramfs:
"cd /usr/share/initramfs-tools/scripts/ && find . -regextype posix-extended -regex '.*/[[:alnum:]_]+$' -type f"