So, please correct me if I'm wrong, but there is no way then to make QTextStream unbuffered, and the only way to reliably output to the console is to write a newline or flush the buffer. It seems true that the text is being held up at QTextStream as you state, since both QTextStream and iostream wrap the same stdout file handle, while iostream "works" for me.

That takes care of my problem, but I still wonder what would cause the same code to execute differently on different computers, and even change how it executes on the same system over time?