I have the same packages for lightdm that xfce-minimal has and my profile looks like this:
##########################################
###### use this file in the profile ######
##########################################
# use multilib packages; x86_64 only
# multilib="true"
displaymanager="lightdm"
# Set to false to disable autologin in the livecd
# autologin="true"
# nonfree xorg drivers
nonfree_xorg="false"
# use plymouth; initcpio hook
plymouth_boot="false"
# use pxe boot; initcpio hook
pxe_boot="true"
################ install ################
# unset defaults to given value
# efi_boot_loader="grub"
# set uefi partition size
# efi_part_size=32M
# unset defaults to given value
# plymouth_theme=manjaro-elegant
# unset defaults to given values
# names must match systemd service names
start_systemd=('avahi-daemon' 'bluetooth' 'cronie' 'ModemManager' 'NetworkManager' 'org.cups.cupsd' 'tlp' 'tlp-sleep')
disable_systemd=('pacman-init')
# unset defaults to given values,
# names must match openrc service names
# start_openrc=('acpid' 'bluetooth' 'cgmanager' 'consolekit' 'cronie' 'cupsd' 'dbus' 'syslog-ng' 'NetworkManager')
# disable_openrc=('pacman-init')
################# livecd #################
# unset defaults to given value
hostname="manjaro-strit"
# unset defaults to given value
username="manjaro-strit"
# unset defaults to given value
# password="manjaro"
# unset defaults to given values
# addgroups="video,audio,power,disk,storage,optical,network,lp,scanner,wheel"
# unset defaults to given values
# names must match systemd service names
# services in start_systemd array don't need to be listed here
# start_systemd_live=('manjaro-live' 'mhwd-live' 'pacman-init')
# unset defaults to given values,
# names must match openrc service names
# services in start_openrc array don't need to be listed here
# start_openrc_live=('manjaro-live' 'mhwd-live' 'pacman-init')
I've tried with non-free drivers true, plymouth boot true, pxe boot false, with all compinations it seems. None of them work.
I'm probably just missing 1 little detail.