Hi,
I do't think you're missing anything. this option only works when VO
is not active. When VO is active, cursor tracking interferes with
the selection process thus things get deselected. If you think about
it, once you turn off cursor tracking using VO keys+shift+f3 then
hold VO keys+cmd to select an item you are doing exactly the same
thing as a sighted user would do as they must hold down the cmd key
as well to select multiple non-contiguous items.
Later...
Tim Kilburn
& Carter the Canine
Fort McMurray, AB Canada