The intended behavior would be something like agnosticism to whether there's a newline or not between the heading and the PROPERTIES drawer, since it seems like drawers aren't needed to be immediately after the heading.

Here's a minimum working example:

* not working flashcard :fc:

:PROPERTIES:
:FC_CREATED: 2024-01-17T12:36:02Z
:FC_TYPE:  normal
:ID:       e2948047-7a9e-4f4c-a85e-dec3d0ec8a8d
:END:
:REVIEW_DATA:
| position | ease | box | interval | due                  |
|----------+------+-----+----------+----------------------|
| front    |    0 |   0 |      1.5 | 2024-01-14T00:36:02Z |
:END:
answer

Here's the error message I get after enabling toggle-debug-on-error and running org-fc-review and selecting the buffer option:

Debugger entered--Lisp error: (error "ID e2948047-7a9e-4f4c-a85e-dec3d0ec8a8d not found ...")
  signal(error ("ID e2948047-7a9e-4f4c-a85e-dec3d0ec8a8d not found ..."))
  (condition-case err (let* ((card (car-safe (let* ((v org-fc-review--session) (x ...)) (prog1 x (eieio-oset v ... ...))))) (path (plist-get card :path)) (id (plist-get card :id)) (type (plist-get card :type)) (position (plist-get card :position))) (let* ((v org-fc-review--session)) (eieio-oset v 'current-item card)) (let ((buffer (find-buffer-visiting path))) (save-current-buffer (set-buffer (find-file path)) (if resuming nil (if buffer (set (make-local-variable ...) t) (set (make-local-variable ...) nil)) (org-fc-set-header-line)) (goto-char (point-min)) (org-fc-id-goto id path) (org-fc-indent) (org-reveal) (org-fc-narrow) (org-fc-hide-keyword-times) (org-fc-hide-drawers) (org-fc-show-latex) (org-display-inline-images) (run-hooks 'org-fc-before-setup-hook) (setq org-fc-review--timestamp (time-to-seconds (current-time))) (let ((step (funcall ... position))) (run-hooks 'org-fc-after-setup-hook) (let ((flip-fn ...)) (if (or ... ... ...) (org-fc-review-rate-mode 1) (org-fc-review-flip-mode 1))))))) (error (org-fc-review-quit) (signal (car err) (cdr err))))
  (if (not (null (eieio-oref org-fc-review--session 'cards))) (condition-case err (let* ((card (car-safe (let* (... ...) (prog1 x ...)))) (path (plist-get card :path)) (id (plist-get card :id)) (type (plist-get card :type)) (position (plist-get card :position))) (let* ((v org-fc-review--session)) (eieio-oset v 'current-item card)) (let ((buffer (find-buffer-visiting path))) (save-current-buffer (set-buffer (find-file path)) (if resuming nil (if buffer (set ... t) (set ... nil)) (org-fc-set-header-line)) (goto-char (point-min)) (org-fc-id-goto id path) (org-fc-indent) (org-reveal) (org-fc-narrow) (org-fc-hide-keyword-times) (org-fc-hide-drawers) (org-fc-show-latex) (org-display-inline-images) (run-hooks 'org-fc-before-setup-hook) (setq org-fc-review--timestamp (time-to-seconds (current-time))) (let ((step ...)) (run-hooks 'org-fc-after-setup-hook) (let (...) (if ... ... ...)))))) (error (org-fc-review-quit) (signal (car err) (cdr err)))) (message "Review Done") (org-fc-review-quit))
  org-fc-review-next-card()
  (progn (setq org-fc-review--session (org-fc-make-review-session cards)) (run-hooks 'org-fc-before-review-hook) (org-fc-review-next-card))
  (if (null cards) (message "No cards due right now") (progn (setq org-fc-review--session (org-fc-make-review-session cards)) (run-hooks 'org-fc-before-review-hook) (org-fc-review-next-card)))
  (let* ((index (org-fc-index context)) (cards (org-fc-index-filter-due index))) (if org-fc-shuffle-positions (setq cards (org-fc-index-shuffled-positions cards)) (setq cards (org-fc-index-positions cards))) (if (null cards) (message "No cards due right now") (progn (setq org-fc-review--session (org-fc-make-review-session cards)) (run-hooks 'org-fc-before-review-hook) (org-fc-review-next-card))))
  (if org-fc-review--session (if (yes-or-no-p "Flashcards are already being reviewed. Resume? ") (progn (org-fc-review-resume))) (let* ((index (org-fc-index context)) (cards (org-fc-index-filter-due index))) (if org-fc-shuffle-positions (setq cards (org-fc-index-shuffled-positions cards)) (setq cards (org-fc-index-positions cards))) (if (null cards) (message "No cards due right now") (progn (setq org-fc-review--session (org-fc-make-review-session cards)) (run-hooks 'org-fc-before-review-hook) (org-fc-review-next-card)))))
  org-fc-review((:paths "/home/mesa/org/temp.org" :filter nil))
  funcall-interactively(org-fc-review (:paths "/home/mesa/org/temp.org" :filter nil))
  call-interactively(org-fc-review record nil)
  command-execute(org-fc-review record)
  execute-extended-command(nil "org-fc-review" nil)
  funcall-interactively(execute-extended-command nil "org-fc-review" nil)
  call-interactively(execute-extended-command)
  god-mode-self-insert()
  funcall-interactively(god-mode-self-insert)
  call-interactively(god-mode-self-insert nil nil)
  command-execute(god-mode-self-insert)

And here's the echo area message I get: condition-case: ID e2948047-7a9e-4f4c-a85e-dec3d0ec8a8d not found in /home/mesa/org/temp.org

For what its worth, I use OpenBSD and org-fc ran fine on it after installing gawk. I don't recall fiddling with anything to make it work out of the box.

I've decided to switch to buku after seeing the kinkspam that this user decided to throw onto the frontpage. Just a heads up.

Also take a look at the tags list on the front page -- it is filled with kink-related tags.