QProgress bar - Busy Indicator - Strange behaviour

[johnnyturbo3]

I'm trying to add a Progress bar as a busy indicator. However, it's behaving strange - the 'progress' only goes a quarter of the way up the bar and then restarts at the beginning. I'm using the following code:

test.cpp

test::test()
{
  QProgressBar *qProBar = new QProgressBar;
  qProBar->setRange(0,0);
 
  QVBoxLayout *mainLayout = new QVBoxLayout();
  mainLayout->addWidget(qProBar);
 
  setLayout(mainLayout);
}

test::test()
{
  QProgressBar *qProBar = new QProgressBar;
  qProBar->setRange(0,0);

  QVBoxLayout *mainLayout = new QVBoxLayout();
  mainLayout->addWidget(qProBar);

  setLayout(mainLayout);
}

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test.h

class test : public QWidget
{
  Q_OBJECT
 
public:
  test();
  ~test();
};

class test : public QWidget
{
  Q_OBJECT

public:
  test();
  ~test();
};

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I couldn't find any similar problems on the net, and the code is as minimal as it can get. Any ideas? Thanks in advance!