I have this issue too (again as it happend for several months…) - but I don’t think it is a patch-issue, but rather a Microsoft Update issue -
After the patch last week everything worked fine, today Windows was updating to 20H2 Build 19042.867 and after this the screens stayed black after starting the sim.
Fixed it for me: Rename (or delete) the folder asobo-vcockpits-instruments in Official/OneStore directory - restart the sim, let it reload the content, screens are back again - not sure for how long, I’m still investigating.