How to ignore the file-tree structure in the results with org-ql-select?

Suppose you have this `test.org` file

``` org
#+TITLE: Test

#+begin_src emacs-lisp
(org-ql-select
nil
'(and (planning :from "2021-08-21" :to "2021-08-30")
(todo))
:action '(list (org-entry-get (point) "TODO")
(concat "[["
(substring-no-properties (org-get-heading t t))
"]]")
(org-entry-get (point) "DEADLINE"))
:sort '(deadline))
#+end_src

#+RESULTS:
| TODO | [[Task 1]] | <2021-08-23 Mon> |
| TODO | [[Task 2]] | <2021-08-27 Fri> |
| TODO | [[Task 3]] | <2021-08-24 Tue> |
| TODO | [[Task 4]] | <2021-08-23 Mon> |

* H1
** TODO Task 1
DEADLINE: <2021-08-23 Mon>
** TODO Task 2
DEADLINE: <2021-08-27 Fri>
* H2
** TODO Task 3
DEADLINE: <2021-08-24 Tue>
** TODO Task 4
DEADLINE: <2021-08-23 Mon>
```

According to the manual the results should be sorted by deadline, but in this case they are showing as appearance in the file. Notice how the deadline dates are completely mixed.

Did I make something wrong?

I'm in this commit 94f9e6f3031b32cf5e2149beca7074807235dcb0

Thanks for the help.