Can someone explain RenderTexture.SupportsStencil

I'm trying to create a RenderTexture of my current scene and everything works as expected. However on a couple of devices (Nexus 7, Galaxy Tab 10), the resulting RenderTexture ignores the stencil buffer that I've used in my textures.

I create a RenderTexture like this:

 PolaroidRenderTexture = RenderTexture.GetTemporary(width, width, 24);
 Debug.Log (RenderTexture.SupportsStencil(PolaroidRenderTexture)); //returns false for the above devices

 RenderTexture.active = PolaroidRenderTexture;
 RenderingCamera.targetTexture = PolaroidRenderTexture;
 RenderingCamera.Render();

I noticed the static function RenderTexture.SupportsStencil in the docs, but it doesn't have a lot of detail. When would this be false? Is it just not supported by some graphic chips? Is there something on my RenderTexture I can change?

Thanks!