ok, so I renamed the “Levels” folder to “Maps”, but I still get the same behavior: Working in editor, black screen when I ‘launch’ it or run the packaged game.
However I noticed something in the console when executing the C++ code:
LogStreaming:Error: Couldn't find file for package /Engine/Maps/Entry requested by async loading code.
I don’t know why the Entry map is requested (I have "/Game/Maps/Transition as transition map) but maybe that’s related to the problem.