QState (and therefore also QStateMachine) want the initial state to be a direct decendant of itself. For example:

QState a;
  QState b(&a);
    QState c(&b);
a.setInitialState(&c); // WARNING: state 0x123 is not a child of this state (0x456)

There is noting preventing a "deep" state as the initial state. The state machine will then enter both b and c whenever a is entered. The check should be changed to see if the initial state has the current state as an ancestor, and not as a direct parent.