When I archive one subtree (C-c $), the first one succeeds.
The second archive operation fails with a permission denied error as shown in the messages buffer:

Copied: Subtree(s) with 11 characters
Saving file c:/users/ian/Dropbox/org/nowtutoradmin.org_archive...
Wrote c:/users/ian/Dropbox/org/nowtutoradmin.org_archive
Cut: Subtree(s) with 11 characters
Subtree archived in file: ~/Dropbox/org/nowtutoradmin.org_archive
Copied: Subtree(s) with 11 characters
Saving file c:/users/ian/Dropbox/org/nowtutoradmin.org_archive...
basic-save-buffer-2: Unlocking file: Permission denied, c:/users/ian/Dropbox/org/nowtutoradmin.org_archive

Noticed this yesterday.  Updated org and all packages, then tried it again today, was able to reproduce it easily
Ian


Emacs  : GNU Emacs 27.1 (build 1, x86_64-w64-mingw32)
 of 2020-08-21
Package: Org mode version 9.4 (9.4-55-g706ba9-elpa @ c:/users/ian/.emacs.d/elpa/org-20201207/)

current state:
==============
(setq
 org-babel-results-keyword "results"
 org-src-mode-hook '(org-src-babel-configure-edit-buffer org-src-mode-configure-edit-buffer)
 org-columns-default-format "%40ITEM(Task) %17Effort(Estimated Effort){:} %CLOCKSUM %CLOCKSUM_T"
 org-link-shell-confirm-function 'yes-or-no-p
 org-metadown-hook '(org-babel-pop-to-session-maybe)
 org-global-properties '(("Effort_All" . "0 0:10 0:30 1:00 2:00 3:00 4:00 5:00 6:00 7:00"))
 org-clock-out-hook '(org-clock-remove-empty-clock-drawer)
 org-html-format-inlinetask-function 'org-html-format-inlinetask-default-function
 org-enforce-todo-dependencies t
 org-odt-format-headline-function 'org-odt-format-headline-default-function
 org-agenda-files '("~/Dropbox/org/organizer.org" "~/Dropbox/org/nowtutoradmin.org" "~/Dropbox/org/testerror.org")
 org-ascii-format-inlinetask-function 'org-ascii-format-inlinetask-default
 org-tag-alist '(("@work" . 119) ("@home" . 104) ("laptop" . 108))
 org-modules '(ol-w3m ol-bbdb ol-bibtex ol-docview ol-gnus ol-info ol-irc ol-mhe ol-rmail ol-eww org-habit)
 org-plantuml-jar-path "/users/ian/plantuml.jar"
 org-blocker-hook '(org-block-todo-from-checkboxes org-block-todo-from-children-or-siblings-or-parent)
 org-mode-hook '(org-clock-load #[0 "\300\301\302\303\304$\207" [add-hook change-major-mode-hook org-show-all append local] 5]
#[0 "\300\301\302\303\304$\207" [add-hook change-major-mode-hook org-babel-show-result-all append local] 5]
org-babel-result-hide-spec org-babel-hide-all-hashes)
 org-clock-persist 'history
 org-odt-format-drawer-function #[514 "\207" [] 3 "\n\n(fn NAME CONTENTS)"]
 org-archive-hook '(org-attach-archive-delete-maybe)
 org-confirm-elisp-link-function 'yes-or-no-p
 org-mime-src-mode-hook '(org-mime-src-mode-configure-edit-buffer)
 org-agenda-before-write-hook '(org-agenda-add-entry-text)
 org-metaup-hook '(org-babel-load-in-session-maybe)
 org-bibtex-headline-format-function #[257 "\300 \236A\207" [:title] 3 "\n\n(fn ENTRY)"]
 org-latex-format-drawer-function #[514 "\207" [] 3 "\n\n(fn _ CONTENTS)"]
 org-babel-pre-tangle-hook '(save-buffer)
 org-file-apps '((auto-mode . emacs) ("\\.mm\\'" . default) ("\\.x?html?\\'" . default) ("\\.pdf\\'" . default)
("\\.xlsx\\'" . default) ("\\.docx\\'" . default))
 org-tab-first-hook '(org-babel-hide-result-toggle-maybe org-babel-header-arg-expand)
 org-babel-load-languages '((emacs-lisp . t) (latex . t) (dot . t) (org . t) (plantuml . t))
 org-agenda-time-grid '((daily today require-timed) (600 800 1000 1200 1400 1600 1800 2000) "......" "----------------")
 org-log-done 'time
 org-link-abbrev-alist '(("gmail" . "https://mail.google.com/mail/?view=cm&fs=1&to=%s"))
 org-ascii-format-drawer-function #[771 " \207" [] 4 "\n\n(fn NAME CONTENTS WIDTH)"]
 org-agenda-span 'day
 org-agenda-loop-over-headlines-in-active-region nil
 org-src-lang-modes '(("plantuml" . plantuml) ("C" . c) ("C++" . c++) ("asymptote" . asy) ("bash" . sh) ("beamer" . latex)
     ("calc" . fundamental) ("cpp" . c++) ("ditaa" . artist) ("dot" . fundamental) ("elisp" . emacs-lisp)
     ("ocaml" . tuareg) ("screen" . shell-script) ("shell" . sh) ("sqlite" . sql))
 org-catch-invisible-edits 'smart
 org-occur-hook '(org-first-headline-recenter)
 org-log-into-drawer t
 org-enforce-todo-checkbox-dependencies t
 org-agenda-include-diary t
 org-cycle-hook '(org-cycle-hide-archived-subtrees org-cycle-hide-drawers org-cycle-show-empty-lines
 org-optimize-window-after-visibility-change)
 org-todo-keywords '((sequence "TODO" "IN-PROGRESS" "WAITING" "DONE"))
 org-speed-command-hook '(org-speed-command-activate org-babel-speed-command-activate)
 org-odt-format-inlinetask-function 'org-odt-format-inlinetask-default-function
 org-babel-tangle-lang-exts '(("latex" . "tex") ("emacs-lisp" . "el") ("elisp" . "el"))
 org-format-latex-options '(:foreground default :background default :scale 2.0 :html-foreground "Black" :html-background
   "Transparent" :html-scale 1.0 :matchers ("begin" "$1" "$" "$$" "\\(" "\\["))
 org-export-before-parsing-hook '(org-attach-expand-links)
 org-confirm-shell-link-function 'yes-or-no-p
 org-link-parameters '(("eww" :follow org-eww-open :store org-eww-store-link)
      ("rmail" :follow org-rmail-open :store org-rmail-store-link)
      ("mhe" :follow org-mhe-open :store org-mhe-store-link)
      ("irc" :follow org-irc-visit :store org-irc-store-link :export org-irc-export)
      ("info" :follow org-info-open :export org-info-export :store org-info-store-link)
      ("gnus" :follow org-gnus-open :store org-gnus-store-link)
      ("docview" :follow org-docview-open :export org-docview-export :store org-docview-store-link)
      ("bibtex" :follow org-bibtex-open :store org-bibtex-store-link)
      ("bbdb" :follow org-bbdb-open :export org-bbdb-export :complete org-bbdb-complete-link :store
org-bbdb-store-link)
      ("w3m" :store org-w3m-store-link)
      ("attachment" :follow org-attach-follow :complete org-attach-complete-link) ("id" :follow org-id-open)
      ("file+sys") ("file+emacs") ("shell" :follow org-link--open-shell)
      ("news" :follow #[514 "\301\300\302 Q \"\207" ["news" browse-url ":"] 6 "\n\n(fn URL ARG)"])
      ("mailto" :follow #[514 "\301\300\302 Q \"\207" ["mailto" browse-url ":"] 6 "\n\n(fn URL ARG)"])
      ("https" :follow #[514 "\301\300\302 Q \"\207" ["https" browse-url ":"] 6 "\n\n(fn URL ARG)"])
      ("http" :follow #[514 "\301\300\302 Q \"\207" ["http" browse-url ":"] 6 "\n\n(fn URL ARG)"])
      ("ftp" :follow #[514 "\301\300\302 Q \"\207" ["ftp" browse-url ":"] 6 "\n\n(fn URL ARG)"])
      ("help" :follow org-link--open-help) ("file" :complete org-link-complete-file)
      ("elisp" :follow org-link--open-elisp) ("doi" :follow org-link--open-doi))
 org-latex-format-headline-function 'org-latex-format-headline-default-function
 org-capture-templates '(("z" "Toefl school entry" entry
 (file+olp "~/Dropbox/org/nowtutoradmin.org" "Tasks (billable)"
  "Contact schoools, consultants re B2B service" "Toefl Schools in NYC")
 "*** %^{School}\n:PROPERTIES\n:web_site: %^{web site}\n:Email_address: %^{email address}\n:Gmail_link: [[gmail:%\\3]]\n:FirstName: %^{first name}\n:LastName: %^{last name}\n:Position: %^{position}\n:datecreated: %u\n:END\n" :jump-to-captured 1)
("n" "Candidate entry" entry (file+olp "~/Dropbox/org/nowtutoradmin.org" "datastores" "candidates")
 "** %^{Candidate} %^g\n:PROPERTIES:\n:Status: \n:Email_address: [[gmail:%^{email address}]]\n:Datecreated: %u\n:Skype: \n:Ranking:\n:Video_url:\n:University_grad:\n:Certified:\n:Years_of_experience:\n:Open_to_onsite:\n:Resume_location:\n:Resume_link:\n:Citizenship:\n:Country:\n:END:\n*** %\\1        :waitreply:sentrequest:\n     DEADLINE: %(org-insert-time-stamp (org-read-date nil t \"+2\"))\n" :jump-to-captured 1)
("s" "Submission entry" entry (file+olp "~/Dropbox/org/nowtutoradmin.org" "datastores" "submissions")
 "** TOSUBMIT %^{Client|Aston|Chengxun|Daqing EF|EF Xuzhou|Jing|Lin Qiu|Micro-Language|Smilekid|Super Small Translation|Wowtalk} %a\n:PROPERTIES:\n:Client: %\\1\n:Candidate: %a\n:Datecreated: %U\n:END:\n" :jump-to-captured 1)
("p" "Protocol" entry (file+headline (\, "~/Dropbox/org/inbox.org") "Web captures")
 "* %^{Title}\nSource: %u, %c\n #+BEGIN_QUOTE\n%i\n#+END_QUOTE\n\n\n%?")
("j" "Journal entry" plain (file+olp+datetree "~/Dropbox/org/journal.org") "%i\n%?\n" :time-prompt 1
 :jump-to-captured 1)
("w" "work log entry" plain (file+olp+datetree "~/Dropbox/org/nowtutoradmin.org" "work log") "\n\n%?"
 :clock-in 1 :empty-lines 1 :jump-to-captured 1)
("L" "Protocol Link" entry (file+headline (\, "~/Dropbox/org/inbox.org") "Web captures")
 "* %? [[%:link][%(transform-square-brackets-to-round-ones \"%:description\")]]\n")
)
 org-link-elisp-confirm-function 'yes-or-no-p
 org-latex-format-inlinetask-function 'org-latex-format-inlinetask-default-function
 org-html-format-drawer-function #[514 "\207" [] 3 "\n\n(fn NAME CONTENTS)"]
 org-html-format-headline-function 'org-html-format-headline-default-function
 org-directory "~/Dropbox/org"
 org-link-from-user-regexp "\\<ian@DESKTOP-5562SOU\\>"
 org-default-notes-file "~/Dropbox/org/notes.org"
 )

--
=====
Ian Garmaise
Consultant
Phorix Solutions Group
ian.g@phorixsol.com
Toronto cell: 416.432.2251
NYC: 917.512.9535

https://www.linkedin.com/in/igarmaise/

http://www.PhorixSol.com