Maybe try this instead (you added the symbol as a list, not just a symbol):

123

#+BEGIN_SRC emacs-lisp
(add-text-properties 1 3 '(invisible hide-this-stuff))
(add-to-invisibility-spec 'hide-this-stuff)
#+END_SRC

#+RESULTS:
: (hide-this-stuff (org-hide-block . t) (org-link) (outline . t) t)

#+BEGIN_SRC emacs-lisp
(remove-from-invisibility-spec 'hide-this-stuff)
#+END_SRC

#+RESULTS:
: ((org-hide-block . t) (org-link) (outline . t) t)


John

-----------------------------------
Professor John Kitchin (he/him/his)
Doherty Hall A207F
Department of Chemical Engineering
Carnegie Mellon University
Pittsburgh, PA 15213
412-268-7803
@johnkitchin
http://kitchingroup.cheme.cmu.edu



On Thu, Jan 6, 2022 at 5:48 PM Enrico Flor <enrico@eflor.net> wrote:

> In a minor mode I wrote for myself, I use add-text-properties to make
> certain things invisible.  This does not work in org-mode, and I don't
> understand why.  For instance, the following has no effect in when the
> buffer is in org-mode (and only when it's in org mode):
>
>     (add-text-properties 1 3 '(invisible t))
>
> Any other text property I try to add does not give me any problem.
> I have also tried to achieve the same by adding things to
> buffer-invisibility-spec, but again, the following has no effect
> whatsoever, if in org-mode:
>
>     (add-text-properties 1 3 '(invisible hide-this-stuff))
>     (add-to-invisibility-spec '(hide-this-stuff))
>
> Can anyone give me a hint as to what is going on?
>
> Thank you.
>