Downloaded the images from:
and found that /etc/writable is empty:
$ ls /etc/writable
$
but /etc has several symlinks that point into it:
lrwxrwxrwx 1 root root 22 Oct 18 15:49 hostname -> /etc/writable/hostname
lrwxrwxrwx 1 root root 23 Oct 18 15:49 localtime -> /etc/writable/localtime
lrwxrwxrwx 1 root root 22 Oct 18 15:49 timezone -> /etc/writable/timezone
I think this causes hostnamectl to fail:
$ sudo hostnamectl set-hostname foo
Could not set property: Failed to set static hostname: Read-only file system