Idk, this sounds like an issue with your specific hardware not with Virtiofs or Unraid.
Edit:
@johnsanc As a side note, the both times I built a PC with an Asrock board it had weird UEFI issues and trouble booting. My old desktop had an Asrock board and it had UEFI issues, at one point I had to swap the BIOS chip because the ME region got corrupted.
I built a machine for a family member with an Asrock board that at times just would refuse to boot. After those experiences I now stick with Gigabyte and Asus. Asrock isn't great based on my experience, so I'm not surprised you flashed your BIOS and can't access it now. You may need to go on eBay and buy a new BIOS chip, they are very easy to change on most boards.
I also wonder, are you using an HBA or onboard SATA for your drives? If onboard SATA I'd wonder if something is up with your motherboard.