Got another observation:

Text content at position 30248:


There is an overlay here:
 From 30248 to 30442
  evaporate            t
  invisible            org-fold-outline
  isearch-open-invisible delete-overlay
  org-invisible        org-fold-outline
  priority             5


There are text properties here:
  fontified            t
  isearch-open-invisible org-fold-core--isearch-show
  isearch-open-invisible-temporary org-fold-core--isearch-show-temporary

Am Sa., 6. Mai 2023 um 08:24 Uhr schrieb Ihor Radchenko <yantar92@posteo.net>:

"Christopher M. Miles" <numbchild@gmail.com> writes:

> I meet an unfold-able headline now. Then I record a video to show this
> unfold-able headline. I executed command "describe-text-properties".

Please put the cursor right before the fold ("..."), execute M-x
describe-text-properties and share the properties description text.
You don't need video to share the property details buffer contents.

--
Ihor Radchenko // yantar92,
Org mode contributor,
Learn more about Org mode at <https://orgmode.org/>.
Support Org development at <https://liberapay.com/org-mode>,
or support my work at <https://liberapay.com/yantar92>