I think the same is true for all nation wide record collections. Once you narrow down to a county/city level in the card catalog, it won't show collections that include more than that specific area. For example, if I narrow down to Philadelphia, it doesn't show the US Federal Censuses either, despite Philadelphia obviously being included in them. I guess it assumes that if you're narrowing down to a city, you're looking for collections specific to only that city. This may very well be the standard for a card catalog. Just something to keep in mind when searching!