Spark Labels disappear when using UIFTETextField

Steps to reproduce:
1. Attached is a sample application project to reproduce the issue. Click on the update button and wait for some time and you can see the labels that are defined at the top text is (Spark Label, Watch me disappearing) will disappear after some time and will never come back till the time the application is restarted or page is refreshed again.

The code consist of spark labels and mx charts that consist of mx labels. So for setting the css the style code is used.

mx|Label,charts|Series, charts|AxisLabel,charts|DualStyleObject, charts|ChartLabel

{ font-family: "ComicSans"; textFieldClass: ClassReference("mx.core.UIFTETextField"); }

Here it is using the UIFTETextField (FTE) as per the documenation link
http://help.adobe.com/en_US/flex/using/WSda78ed3a750d6b8f-26a13bbf123c441239d-8000.html

One observation is the same code works fine with FP 10.0 and labels disappear with FP 10.1.

Actual Results:
The spark Labels are disappearing.

Expected Results:
The spark labels must not disappear.

Workaround (if any):
Comment the existing style code
mx|Label,charts|Series, charts|AxisLabel,charts|DualStyleObject, charts|ChartLabel

{ font-family: "ComicSans"; textFieldClass: ClassReference("mx.core.UIFTETextField"); }

Uncomment the style declaration

mx|Label,charts|Series, charts|AxisLabel,charts|DualStyleObject, charts|ChartLabel

{ font-family: "ComicSansDF3"; }

And you will not see the labels disappearing.
Embed font twice, once with ComicSans and once with ComicSansDF3. But embedding a font twice isn't really an acceptable long term solution. The attached application demonstrates the issue.
Further to this, we have also observed that there is a significant performance difference between using the new text flow engine in MX components, and using the 'old' approach. This happens in both 10.0 and 10.1 of the flash player.