MacBook Pro no longer sends a signal to an external display after sleep

Case

I extend my MacBook Pro 2019 (Sonoma 14.2.1) with a Samsung Odyssey G9 49 inch ultra wide monitor using a displayport 1.4 cable. Everything worked fine for 2 weeks until I put my MacBook to sleep while in clamshell mode.

Problem

When I tried to wake it up it no longer sends a signal to the external screen. Replugging the cable will wake up the external screen backlight but then shows "No signal". In the "Displays" section I see a brief flicker of another screen which dissapears quickly showing only the native MacBook screen. Regardless of what usb-c port is used, even when using a different screen using hdmi instead of DP1.4, the MacBook remains completely unresponsive to attempts to connect another display. I have to turn off the mac and screen to fix the external screen but only temporary because the mac will enter sleep at some point.

What I have tried

1. Reset the NVRAM (does nothing)
2. Reset SCM (does nothing)
3. Reset PRAM (does nothing)
4. Put mac to sleep and wake it up both in clamshell mode and normal node (does nothing)
5. Detect screen in the Displays section (does nothing)
6. Tried with and without battery (does nothing)
7. Tried with enforcing to use only the non-integrated video card (AMD Radeon Pro 5300M) in Battery -> Options -> Automatic graphics switching (does nothing)
8. Verified my MacBook Tech Specs using its serial number, yes it supports DisplayPort!
9. Updated to the latest monitor hardware drivers
10. Updated to the latest iOS (Sonoma 14.2.1)
11. If your Mac doesn’t recognise an external display
12. External display says No Signal
13. Everything else Apply support suggests to fix it

Then I started to do a "try all combinations with cables plugged/unplugged and macbook and or screen on/off, about 16 different combinations".

The only combination that would get the screen working is if I shutdown the MacBook (resetting does not work) and power off the external display, then boot the macbook and wait for it to startup, then turn on the external monitor and voila it works. But if it goes to sleep afterwards I have to repeat this entire process.

Known problem for over a decade

I searched on the internet and discovered that this problem has been around for more than a decade and appears in various forms. Even the Apple discussions/support pages list these problems but still there is no fix and macbook owners receive the same instructions assuming these will fix the problem. We have gotten to the point where it is clear this is a software problem and a bug report should be send to Apple developers to see what is going on.

MacBook crashes sometimes when try to wake it up

When I power on my macbook and then power on the screen, everything works (with the lid open this time). Then I let it go into sleep mode after which I wake it up using space bar. The macbook screen is black while the keyboard backlight and magic touch bar light up.

After 2 minutes; an error message appears on the (black) screen in white letters in 8 languages after which it either shuts down my macbook entirely or I get back to my desktop with an error message dialog. The dialog error detail report mentions something about the WindowServer. I tried to sudo killall -HUP WindowServer but restarting it wouldnt do anything.

This is very likely a software problem, why?

I am lucky to have two of the same MacBooks, the first Macbook (A) is now permanently bugged and non-responsive to any external display being connected after the macbook awakes from sleep. The second MacBook (B) however is not bugged (yet), so what happens when I insert the cable into MacBook B? It works! Also when I alternate between macbook A and B, Macbook B always works while Macbook A does not. Conclusion; nothing wrong with the external monitor or macbook hardware which leaves only the macbook software!

Rationale

My educated guess as a software engineer:

• It seems like some initial registry value is set during startup which allows the screen to connect while sleepmode alters this value preventing the screen to connect in future attempts. Since a full shutdown is required to fix the problem and a reboot does not work, this buggy value somehow persists over a reboot.
• In case the macbook sends out a signal to the external screen to wake it up and expects a timely response but the external display fails to do so in time, might cause the macbook to not send a signal to the external display since it assumes there is no external display.

I would assume that reinstalling iOS will return my MacBook to the non-buggy state but that solution is far from practical.

Apple could you please pick up this issue and start debugging and fixing it? More and more people are using wide monitors that are not native Apple hardware. This issue has not been resolved for a long time and we hope this is taken serious and forwarded to people that can solve this issue.

Thanks in advance