Already added People are not listed when adding someone to e.g. Family

I added one person XYZ to "All People". Then I went to Worlds > Family > "+ Add person". I would have expected that the person XYZ would appear when entering their name or be listed. But when I enter "XYZ" it just creates a second person with that name in "All people". (I know that I could have added XYZ to the world "Family" from within "All people" view instead).