Fedora core addidng package for booting into ram

Hi everyone, hope for your help.
I have encountered the following problem:
following the instructions to boot the operating system into RAM https://docs.fedoraproject.org/en-US/fedora-coreos/live-booting/ i needed to add some packages to live-rootfs. to boot via PXE. but if i just unpack this archive and pack it back up - the system does not boot anymore. tried without changes just to repack the CPIO archive and the system does not accept it either.
used the following commands :
extract “cpio -i < live-rootfs”
package “find ./ | cpio -H newc -o > /tmp/live-rootfs”