An element in a Group container will disappear if - brought to the top of the group using setElementIndex, then changing the state of of the application.

<s:Application xmlns:fx="http://ns.adobe.com/mxml/2009"
xmlns:s="library://ns.adobe.com/flex/spark">

<s:states>
<s:State name="state1"/>
<s:State name="state2"/>
</s:states>

<s:controlBarContent>
<s:Button label="Change State" click="currentState=currentState=='state1'?'state2':'state1'" />
</s:controlBarContent>

<s:Group id="group1">
<s:Button id="btn1" label="1" click="group1.setElementIndex(btn1, 1)" x="50" y="50"/>
<s:Button id="btn2" label="2" includeIn="state2" x="65" y="65" />
</s:Group>

</s:Application>

Steps to reproduce:
1. Click "Change State" button
2. Click the "1" button to bring it to the front
3. Click "Change state"
4. Click "Change state" again
5. Notice that button 1 disappears.

Actual Results:

button 1 disappears.

Expected Results:

button 1 should still be visible

Workaround (if any):