I have noticed a new issue that happens for me since updating to Starling 2.x.
In a Windows AIR app, I use the AssetManager to load an embedded spritesheet and no external assets. I use textures from the spritesheet to skin buttons in Feathers. If the screen locks and is then unlocked the textures of the buttons vanish and are not restored.
In doing some test, I found that if I loaded a non-embedded assets (just a 1x1 png file) it stopped the textures from vanishing.
Unsure what is happening here but thought I'd post my results in case a fix is required or someone else has this issue.