The “Smart Album” in Nitro is just an empty container with a query attached to it. That’s why it’s empty in Photos – it only gets “filled” when you view it in Nitro, but the images there are transient – they are not added officially to the album. I suppose it could be made more permanent, but that’s not the intent of the feature (since it’s inherently dynamic).
It is akin to a Smart Folder in the Finder – smart folders are not really folders. They looks like folders in the Finder, but if you cannot use it outside of the Finder (like in an Open Dialog).
