Just another check on my side for any appearance of "org-fold-": Nothing in
my code, only org related packages use it.

$ grep -r -l org-fold- .
./org/.git/index
./org/doc/org-manual.org
./org/etc/ORG-NEWS
./org/lisp/ob-core.el
./org/lisp/ob-exp.el
./org/lisp/ob-lilypond.el
./org/lisp/ob-ref.el
./org/lisp/ol.el
./org/lisp/org-agenda.el
./org/lisp/org-archive.el
./org/lisp/org-capture.el
./org/lisp/org-clock.el
./org/lisp/org-colview.el
./org/lisp/org-compat.el
./org/lisp/org-crypt.el
./org/lisp/org-cycle.el
./org/lisp/org-element.el
./org/lisp/org-feed.el
./org/lisp/org-fold-core.el
./org/lisp/org-fold.el
./org/lisp/org-footnote.el
./org/lisp/org-goto.el
./org/lisp/org-id.el
./org/lisp/org-inlinetask.el
./org/lisp/org-keys.el
./org/lisp/org-lint.el
./org/lisp/org-list.el
./org/lisp/org-loaddefs.el
./org/lisp/org-loaddefs.el~
./org/lisp/org-macs.el
./org/lisp/org-mobile.el
./org/lisp/org-mouse.el
./org/lisp/org-refile.el
./org/lisp/org-src.el
./org/lisp/org-table.el
./org/lisp/org.el
./org/lisp/ox-org.el
./org/lisp/ox.el
./org/testing/lisp/test-org-fold.el
./org/testing/lisp/test-org-list.el
./org/testing/lisp/test-org.el


Am Di., 9. Mai 2023 um 09:58 Uhr schrieb Thomas S. Dye <tsd@tsdye.online>:

>
> Ihor Radchenko <yantar92@posteo.net> writes:
>
> > "Thomas S. Dye" <tsd@tsdye.online> writes:
> >
> >>> You can try
> >>> M-x debug-on-variable-change <RET> org-fold-core-style <RET>
> >>
> >> In case it's helpful, I set debug-on-variable-change as you
> >> suggested but was bitten by the bug without triggering the
> >> debugger.
> >
> > Which likely means that something is calling folding functions
> > from
> > outline.el instead of Org-native folding.
>
> Excellent!
>
> Would it be useful for me to search for calls to the folding
> functions from outline.el in the source code of the Org packages
> that Spacemacs and I load?
>
> If so, tips on how to do this efficiently are welcome.
>
> All the best,
> Tom
>
> --
> Thomas S. Dye
> https://tsdye.online/tsdye
>