I am having a very similar issue. My error is; Fatal error!
Unhandled Exception: EXCEPTION_INT_DIVIDE_BY_ZERO
0x00007ff6d8fff8b6 UnrealEditorFortnite-Win64-Shipping.exe!UnknownFunction
0x00007ff6d91dd666 UnrealEditorFortnite-Win64-Shipping.exe!UnknownFunction
0x00007ff6d91dba2c UnrealEditorFortnite-Win64-Shipping.exe!UnknownFunction
0x00007ff6e97e03aa UnrealEditorFortnite-Win64-Shipping.exe!UnknownFunction
0x00007ff6e97c685a UnrealEditorFortnite-Win64-Shipping.exe!UnknownFunction
0x00007ff6d98b94fe UnrealEditorFortnite-Win64-Shipping.exe!UnknownFunction
0x00007ff6d9b1c734 UnrealEditorFortnite-Win64-Shipping.exe!UnknownFunction
0x00007ff6d9b255ec UnrealEditorFortnite-Win64-Shipping.exe!UnknownFunction
0x00007ff6d9b2567a UnrealEditorFortnite-Win64-Shipping.exe!UnknownFunction
0x00007ff6d9b265b0 UnrealEditorFortnite-Win64-Shipping.exe!UnknownFunction
0x00007ff6d9b31ad4 UnrealEditorFortnite-Win64-Shipping.exe!UnknownFunction
0x00007ff6ef8fac92 UnrealEditorFortnite-Win64-Shipping.exe!UnknownFunction
0x00007ffe3d6e7344 KERNEL32.DLL!UnknownFunction
I do not even get to the templates. It starts to load the template screen and crashes before the projects show up. Unreal Editor (regular) launches normally, UEFN crashes.