Monitor occasionally fails to wake up from standby, boots on black screen afterward

A very bizarre issue keeps occurring on my mother’s computer. Just like mine it uses Manjaro: For me this problem never happens, whereas for her it started happening recently possibly after moving from openSUSE to Manjaro. Fortunately it’s quite rare but problematic when it occurs.

Sometimes when the monitor goes into standby, it never comes back online once the mouse and keyboard are operated: The computer needs to be blindly turned off, though pressing the power button a few times and waiting will result in a clean shut down.

The truly strange part is that next time the machine is booted, it lands on a black screen instead of seeing the login screen (SDDM). This time the screen isn’t powered off: It’s online and connected, but it displays the color black. The machine seems to be operating as normal behind that: If I’m to blindly type the password, I can tell it’s logging in though even after that the screen remains black.

The problem appears to solve itself after several cycles of shutting down and powering back on: At some point the screen just starts working again and you see the login screen as normal. This is not a hardware issue but software driven: The screen never has issues in the boot loader or before then, it’s simply the system not drawing to it after startup… while this happens I can press buttons on the monitor and operate the OSD normally which shows the proper resolution and refresh rate.

Does this issue sound familiar to anyone, and do you know what could be causing it? What can make a failed attempt to wake the screen out of standby modify the OS’s configuration in such a way that it then boots to a black screen after restarting? She’s on an AMD card with the amdgpu module, we’re both on the KDE version of Manjaro stable. My monitor is connected via DisplayPort whereas hers on HDMI.

I does sound familiar to me, I had something similar happen to me twice some days ago, my screen just would not display anything after a shutdown, the fix for me was turning the pc off and waiting a few minutes to turn it on again, or the more recent was taking of the GPU and putting it back again.
Apparently it’s a Manjaro or software issue as you said.

Did you manage to fix it? I’m having the same issue.