Search / Find Contacts / is any contact type / with [tag] only returns individuals

In trying to get a list of all contacts with a certain tag, I went to Search / Find Contacts and left all criteria blank except for the tag. The resulting list of contacts includes only individuals, even though I know some households should be included. If I limit the search to households, three records come up. However, these households do not come up if I leave the contact type blank (any contact type).