Display Alt stopped working GA402RJ

[Exenko]

Hello everyone,

I have a Asus Zepherus GA402RJ who's ability to extend my display with a USB C dock suddenly stopped working. I can still use the dock with my work laptop just fine so I know it is not the cables, dock, monitors, or peripherals. 
First thing I tried was updating all of my drivers using Armory Create, AMD adrenalin, and windows update. I then went into device manager and found out I had to enable either the integrated or dedicated GPU as it had somehow been disabled. This allowed me to use 1 of my external monitors using the dedicated HDMI port but I would far rather be able to use both of my external monitors with the 3.2 USB-C port on the left side of the device. 
I tried updating the bios to the latest version and tried updating the bios to the "USB 4" version after hearing that it helped some users with the same problem but I was not fortunate enough for that to have worked. Power and peripherals data still goes over the dock I just cannot figure out how to get the monitors to display over the type C connection even though it has worked since I bought the computer and the hardware still works with my work laptop. Any help would be greatly appreciated and thanks in advance!

[Falcon2_ROG]

@Exenko 
Please confirm whether the BIOS version and system version of your laptop have been updated to the latest. Additionally, please check if connecting the monitor directly to the laptop’s USB-C port displays the screen properly. If it does, the issue may be caused by a malfunction of your USB-C dock. We apologize for any inconvenience caused.
[Windows 11/10] Troubleshooting - USB Type-C issues

[Exenko]

@Falcon2_ROG thank you for responding, direct connection between a monitor supporting Display Alt does not yield anything. 

I was on:

BIOS Update for Windows

Version 319 10.98 MB 2023/08/11

SHA-256 ：B2AC90DF11244B0E7350D28EE8F1B2F585891A95AF0648CAC0B43F3929032AD1

then I updated to: .505.U4.
following the instructions posted here: https://rog-forum.asus.com/t5/faqs-laptops-desktops/gaming-nb-zephyrus-2022-ga402r-series-usb4-featu... 

work pc -> dock -> external 1
                          -> external 2
                          <- peripherals
                          <- charging
personal GA402RJ -> dock -x-> external 1
                                            -x-> external 2
                                            <- peripherals
                                            <- charging
I can do personal GA402RJ -> HDMI -> external monitor (1 or 2 but not both) so that should rule out the MUX being the issue. 

I would think that if the dock, cables, and monitors all work for the work laptop that would rule out those being a part of the failure chain. the fact that I can rule out the MUX due to being able to use the HDMI port and I can accept peripherals and power into the GA402RJ through the type C dock but not send display alt is what has me lost. Thanks again for any and all help!

[Falcon2_ROG · Accepted solution]

@Exenko 
If there is no signal when connecting the monitor directly (not through the dock), and the issue persists after troubleshooting according to the FAQ mentioned above, it is possible that the USB-C hardware is faulty. We recommend backing up your data and sending the laptop to a service center for further inspection.
The following is the contact information:
https://www.asus.com/support/service-center-location 

Also you can contact the local service center for help.
The following is the contact information:
https://www.asus.com/support/CallUs# 

Sorry for any inconvenience it may be caused.