[RPi4B] No 4k output, 4k missing in both Resolution and Whitelist

Hello,

I've recently upgraded my AVR to a 4k-capable model but I don't seem to be able to get 4k video to my TV anyway. I think it's an issue with my RPi settings because when playing a 4K media my AVR shows it's receiving 1080p@60Hz signal and, obviously, TV shows it's receiving 1080p@60Hz signal. I went over https://wiki.libreelec.tv/configuration/4k-hdr but I've noticed I'm missing all 4k/2160p resolutions in Whitelist (as well as in Resolution settings). I've tried adding hdmi_enable_4kp60=1 to config.txt and modify dtoverlay, no change. Changing other settings as per the article didn't help as well, the only noticeable change was that switching Adjust Refresh to start/stop change the output to [email protected] during playback.
I've searched for quite a bit now but I can't find neither a solution nor the possible root cause. I will appreciate every suggestion Thanks!

HW:
Raspberry Pi 4 Model B 4GB
Argon USB-C 5.25V⎓3.5A brick
Argon ONE M.2 Case with Transcend MTS820S
Onkyo TX-NR686 4k A/V receiver - RPi HDMI0 connected with HDMI 2.1 certified cable (checked by scanning the label on packaging) to HDMI1 (4k)
TCL 55C835 4k TV - AVR connected with HDMI 2.1 certified cable (checked by scanning the label on packaging) to HDMI4 (4k@60Hz)

SW:
LibreElec 10.0.4
latest GoogleTV

config.txt:

# SPDX-License-Identifier: GPL-2.0-or-later
# Copyright (C) 2009-2014 Stephan Raue ([email protected])
# Copyright (C) 2016-present Team LibreELEC (https://libreelec.tv)
################################################################################
# Bootloader configuration
# config.txt version v1 (do not remove or change this line!)
################################################################################
# For more options and information see
# http://rpf.io/configtxt
################################################################################
disable_splash=1
# Default GPU memory split, 76MB are needed for H264 decoder
gpu_mem=128
hdmi_enable_4kp60=1
cec_osd_name=KODI
################################################################################
# Include distribution specific config file if it exists.
################################################################################
[all]
include distroconfig.txt
# uncomment to enable infrared remote recevier connected to GPIO 18
dtoverlay=gpio-ir,gpio_pin=23,vc4-kms-v3d,cma-512
program_usb_boot_mode=1
dtparam=i2c=on
enable_uart=1

I figured it out - my EDID was "stale", still thinking the old AVR is connected to HDMI0. I ran getedid delete and I removed vc4-kms-v3d,cma-512 from config.txt as it wasn't doing anything for me. I still don't have 4k@60Hz but I don't really care as most of the media I play don't go above 4k@30Hz anyway.

Whitelisting resolutions as per the wiki article doesn't work for me for some reason (output resolution get's stuck at 1080@24Hz regardless of source) so I left the whitelist empty. I did apply every other setting metioned there though.