The property stepSize is improperly honoured in a slider that does not start from 0. This is trivially demonstrated by this example:

Slider {
	from: 1
	to: 3
	stepSize: 1
	snapMode: Slider.SnapAlways
	onValueChanged: console.log(value)
}

The slider should have 3 positions: 1, 2, 3. However, it snaps at 1, 1.66, 2.33 and 3. If the slider runs from 0 to 2, the step size is correct.