Thanks for the quick reply, I may have spoken too soon it is not actually rebuilding the entire engine, but doing this:
1>------ Build started: Project: ShaderCompileWorker, Configuration: Development_Program x64 ------
1> Target is up to date
2>------ Build started: Project: BrickRigs, Configuration: Development_Game x64 ------
2> Performing full C++ include scan (building a new target)
2> Creating makefile for BrickRigs (UnrealBuildTool.exe is newer)
2> Building UnrealHeaderTool…
2> Target is up to date
2> Parsing headers for BrickRigs
2> Running UnrealHeaderTool “D:\Unreal Projects\BrickRigs\BrickRigs.uproject” “D:\Unreal Projects\BrickRigs\Intermediate\Build\Win64\BrickRigs\Development\BrickRigs.uhtmanifest” -LogCmds=“loginit warning, logexit warning, logdatabase error” -Unattended -WarningsAsErrors
2> Reflection code generated for BrickRigs in 27.9298939 seconds
2> Performing 305 actions (4 in parallel)
2> PCH.CoreUObject.h.cpp
2> PCH.Core.h.cpp
2> PCH.EnginePrivate.h.cpp
…