Just to add to the above failure, if I first package the customized scene then use the Simulation 3D Scene Configuration block to specify the packaged executable, Simulink doesn't seem to recognize the newly packaged scene but provides a warning:
This means that the packaged scene (named "CircleTrack") wasn't recognized. And another thing observed in UE4 is that, all the pre-built scens have a Data Asset object alongside the Level map, but my customized scene doesn't have it, and I don't know if or how to create that Data Asset object for my customized scene:
I think missing the Data Asset object might be connected to both the failures (either in Unreal Editor mode, or in packaged executable form). If I right click on any of the Data Assets under Content/Maps folder, it points to the C++ file PrimaryAssetLabel.h, which is non-existing in the AutoVrtlEnv project.
So if someone knows how to create this Data Asset, it might solve my problem. Thanks for any hint.