A Blueprint subsystem does not get created in a packaged build
The subsystem collection scans for subclasses once, when it is initialized, and sees only classes already in memory. In a packaged build, a Blueprint class that has not been loaded by then is missed entirely: its CDO is never asked whether to create an instance. The Blueprint logic never runs, and the missing class produces no error or log entry. In the editor, the Content Browser can keep the class loaded and hide the problem.