Widget does not appear in gallery If widget extension is not sandboxed

I have a bundled application that contains a widget extension. On launching the application once the widget appears in the widget gallery, However, I have observed that If my widget extension is not sandboxed, the widget fails to show in the widget gallery. Is this expected? I am using the same xcode project and just that AppSandbox capability for the widget extension target is causing this. Can someone please explain why is this happening?