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PlayStandaloneLocalPc is used when user launches Standalone Game from editor, which loads the .uproject from UE4Editor in Engine binaries instead of loading project from project binaries.
NewSession->ProcessHandle = FPlatformProcess::CreateProc(*GamePath, *Params, true, false, false, NULL, 0, NULL, NULL);
Result:
Break point hit and "Params" is using UE4Editor.exe and passing in .uproject to load project instead of launching binary of project, which can cause issues loading script files
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-36422 in the post.