Thread:Help talk:Tree format/Tree format query does not render as a nested list

Hi everyone,

I'm a bit of a SMW beginner and I was just recently playing around with this result format.

Unfortunately, I don't seem to understand how it is supposed to work.

If I take the example query from the help page and substitute Category:Place with Category:City, it just renders a plain, old unordered list without any nesting.

Example:

Result:

Shouldn't the cities be grouped by country, or am I misunderstanding something here? Or do I need to include the parent pages in the query somehow?