hi @NotTheFed ,
Check setup as in
GPU Lightmass Global Illumination in Unreal Engine | Unreal Engine 5.1 Documentation
also check hardware settings
Hardware and Software Specifications for Unreal Engine | Unreal Engine 5.3 Documentation
The error comes from trying to create a large nanite area
Create a blank project and add/import each asset then turn on nanite for each asset
probably find one asset crashes ue5
dx11 disables nanite .
you may need a bigger pagefile.sys to cope with large nanite assets from mega scans