Engine source file NavArea.h error when building project

When I try and package the game it gives me this error - UE_4.25\Engine\Source\Runtime\NavigationSystem\Public\NavAreas/NavArea.h(10): fatal error C1083: Cannot open include file: ‘NavArea.generated.h’: No such file or directory

I’ve tried reinstalling the engine, migrating to a clean project, compiling the project and editing the NavArea file (even though its an engine file and is meant to be read only).
Any help would be appreciated.