Create a simple Qt console application ( from other, QtConsole application ) with just the main.cpp file having the following code and everything set to default config ( shadow , build , just for one Qt version , the included one ) :

#include <iostream>

int main(int argc, char *argv[])

So a simple hello world. Now set a breakpoint on the single line of code ( std::cout<<"hello world"; ) and try start debugging ( F5 ).
The application will run and end , printing hello world as desired. The debugger however will never stop at the breakpoint. That's because the application finishes before it can attach ( you get the message "During startup program exited with code 0x0" ).
This is clearly a bug in the way the debugger handles attaching to the thread of the running program, it should sync somehow and not let the program finish before it connects to it.
Cause is of course the short program and having some serious hardware , see Environment.

I can reproduce this everytime I try.