Cannot set background/foreground color of QStandardItem in QListView

I have a QListView, where I try to change the color of some of the items, but sadly it doens't work the provided stylesheets.
```
item = self._list_data_model.item(index)

# Change color of item
item.setForeground(color)
item.setBackground(colo1)
```
How can I make it work?