TLDR : This issue is caused by Nvidia driver refusing to be loaded when a virtural enviroment is detected.
The Easy Work Around
For most scarinos, setting the Hyper-V option to No
1. Go to VMs tab
2. Go to edit VM's Configuration
3. Switch to "Advance Mode"
4. Disable Hyper-V
The More "Advanced Work Around"
This method is for one's that turning hyper-v off does not help, In this method We'll be patching the nvidia drive.
Requirement:
Other
Just in case anybody has had the same experience as me; none of the posted suggestions or steps helped me while attempting to fix this GPU passthrough problem (on both Mac and W10 VMs). After countless hours of troubleshooting, my solution (frustratingly simple) was booting Unraid into legacy mode instead of UEFI/efi mode. The moment I decided to boot into legacy and then fire up the vm's, I had no issues with installing the appropriate Nvidia drivers on either operating system's vm.