With so many various solutions randomly working for some people but then not others who literally have the same EXACT settings, I think its pretty clear that this is just a major issue that EPIC has to fix.
If RHI is set to Direct X12 on a machine and worked for Preview 2 and versions prior but suddenly doesn’t work now, then the problem can’t be with peoples computers or OS.
Something is definitely bugged in the new Official 5.0 build.