Label shows no text when height < 12 and maxDisplayedLines="1"

Steps to reproduce:
1. Compile & run:
<?xml version="1.0" encoding="utf-8"?>
<s:Application xmlns:fx="http://ns.adobe.com/mxml/2009"
xmlns:s="library://ns.adobe.com/flex/spark"
xmlns:mx="library://ns.adobe.com/flex/mx">
<fx:Declarations>
<!-- Place non-visual elements (e.g., services, value objects) here -->
</fx:Declarations>

<s:Group>
<s:HGroup verticalAlign="baseline" alignmentBaseline="30" height="80%">
<s:CheckBox id="cb" label="One check box" height="50%" />
<s:Label id="lbl" text="...and some random text..." height="60%" />
<s:Button id="btn" label="and a Button!" height="80%"/>
</s:HGroup>
</s:Group>

</s:Application>

Actual Results:
The CheckBox text is gone and the heights of the children are unknown.

Expected Results:
CheckBox text should appear.

Workaround (if any):