Building the Engine in Visual Studio will fail due to an unresolved external symbol error if a new global variable is added to CoreGlobals.h and then referenced elsewhere in the Engine code. The build will only complete successfully if a full rebuild is performed.
The build will fail with an unresolved external symbol error similar to the following
The build completes successfully.
Perform a full rebuild of the UE4 project.
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-54967 in the post.