Same here. I have done a lot of tests with edid patcher in config.plist or with overrides file in /System/Library/.../Overrides like suggested
in this post.
But no success. I have even test in Catalina and the behavior was exactly the same as on bigsur.
I can see the display in Io registry explorer, I can override the edid but the screen is always black and not detected in settings.
If have override the edid of the internal screen with a bad edid(like the one of my external screen), all screens are disabled(that make sense and prove that the edid override works but is not the problem).
I have the impression that this is an issue related specifically on hp spectre 2020.
All the topics I have found about this issue what either bigsur problem(no ice lake proc and 4k screen, but working on Catalina) or another issue that was resolved with an edid patching(like on Dell XPS 13 9300 that have ice lake).
Anyone have any clue on this problem ?