Okay so I think I just got it on mine. Asrock b450m mobo w/2200g and 2666mhz gskill ram.
1. Downloaded and put instant flash 2.2 bios update onto usb stick
2. I installed the chipset from the mobo disc
3. updated to newest chipset build from amd's website
4. Installed newest igpu drivers from AMD's website
5. Same issue, black screen after boot/crashing instantly at desktop
6. Did instaflash update on bios to 2.2
Whether or not this is the way to do it idk, but it worked. Boots to desktop and doesnt crash anymore, running on Vega 8! What a pita lol
I am having similar issues, currently I am using a dedicated GPU rather than Onboard APU.
This is not ideal but I don't have time to spend time on this broken platform. AMD should provide more stable software before releasing products