I have this HSlider:
<s:HSlider minimum="0" maximum="1" value=".7" stepSize=".1"/>
When my app starts, the Slider ball is at the very far right of the component. It's reporting the value (.7) properly to an item that's bound to it, it just doesn't display it visually. I can then drag the ball around and it will behave as you'd expect.
I'm running SDK 12891.