Unreal Engine Source Build - Assertion Failed for Is Valid(PlatForm)

0]LogCore: Error: appError called: Assertion failed: IsValid(Platform) [File:Runtime/RHI/Public/DataDrivenShaderPlatformInfo.h] [Line: 221]

I keep getting this error when trying to run my development server with the source build. Tried editing the default RHI, and still nothing.