App hangs when clicking button inside imported swf

Hi all,

          been bangin my head against a wall all day, thought I'd see if anyone can shed some light on this -

I have an iOS air app that imports a remote swf. Once imported, an event listener is added to a button inside the imported swf. Clicking the button causes the app to hang. Here's some code -

private function loadRemoteSWF():void{
     var urlRequest:URLRequest = new URLRequest("http://www.domain.com/remote.swf");
     var loader:Loader = new Loader();
     loader.contentLoaderInfo.addEventListener(Event.COMPLETE, onLoaded);
     loader.load(urlRequest);
}
private function onLoaded(e:Event):void{
     var loaderInfo:LoaderInfo = e.currentTarget as LoaderInfo;
     var adPanel:MovieClip = loaderInfo.content as MovieClip;
     adPanel.continueButton.addEventListener(TouchEvent.TOUCH_BEGIN, onContinueClicked);
     addChild(adPanel)
}
private function onContinueClicked(e:TouchEvent):void{
     trace("onContinueClicked");
}

I'm using Flash Builder 4.7 AIR SDK 3.5 ASC 2.0.

This only happens on a release build, debug builds work fine so near impossible to find the cause. It also works fine when using the legacy compiler on the same SDK version.

Dispatching a touch event programatically on the button also works fine. (thought I could do a try/catch to find an error)

adPanel.continueButton.dispatchEvent(new TouchEvent(TouchEvent.TOUCH_BEGIN));

Touching the button just kills the app, it doesn't even hit the trace.

Anyone got any ideas how to debug this, or why this problem might be happening?

Thanks

Dave