Hey there @curtis_bryce! Welcome to the community! So 5.1 uses Shader Model 6 (SM6 as you’ll usually see it) and requires incredibly up to date drivers to work. If at all possible, open up your Geforce experience application and update your drivers. You can either go with the most recent game ready drivers, but I usually recommend to swap them over to studio drivers for better performance/stability in Unreal. Give that a shot, restart your computer, then try the launch again.
If that fails, I have a thread of possible fixes that can stop graphical issues. Not all of them will apply to you, like downgrading to DX11 will work but obviously disables Nanite and Lumen which is a problem. Most of the others are made to reduce overhead on your GPU, solve a shader issue (yours), or a GPU crash from software like Rivatuner, MSI afterburner, or an overlay/gpu capture like Shadowplay(This is possible for you since Nvidia).
However if the issue is based on DX12 changes with Windows 11 this will get much harder to work with! Let me know how it all goes!