Unable to compile when using FReadScopeLock

Attempting to initialize FReadScopeLock with FMultiReaderSingleWriterGT* causes unresolved external errors.

1. Open UE4 Editor
2. Add code to project based on Actor (MyActor)
3. Add the following to MyActor.h
   • Include

     #include "Runtime/Core/Public/HAL/ThreadingBase.h"
     

   • Inside class declaration

     private:
     	FMultiReaderSingleWriterGT mSyncObject;
     

4. Add the following to MyActor.cpp
   • BeginPlay() function

     FReadScopeLock Something(&mSyncObject);
     

5. Compile

Result:
Unresolved external error

Expected:
Compile succeeds since FReadScopeLock takes FMultiReaderSingleWriterGT* as a constructor parameter