Merely a substitute approach using org-occur that works (in spite of a wrong type argument message).

*.org:

* code

[same as in the original]

Matches baz as expected.
#+begin_src emacs-lisp
 (org-occur ":header-args: :tangle[[:space:]].+$")
#+end_src


* sample

[same as in the original]

** baz
:PROPERTIES:
:header-args: :tangle "/path"
:END:

*Messages*

Executing Emacs-Lisp code block at position 513...
org-babel-execute-src-block: Wrong type argument: integer-or-marker-p, nil