problem with org-capture for calendar invite

["Fraga, Eric" <e.fraga@ucl.ac.uk>]

For a long time, I have been using this template for org-capture:

#+begin_src emacs-lisp
  (add-to-list 'org-capture-templates
               '("#"
                 "used by gnus-icalendar-org"
                 entry (file+olp+datetree "~/s/notes/diary.org")
                 "%i"
                 :immediate-finish t))
#+end_src 

For some reason, this no longer works and I get the following error:

,----
| Debugger entered--Lisp error: (error "Capture abort: Missing initial annotation in this ...")
|   signal(error ("Capture abort: Missing initial annotation in this ..."))
|   gnus-article-read-summary-keys(nil)
|   funcall-interactively(gnus-article-read-summary-keys nil)
|   call-interactively(gnus-article-read-summary-keys nil nil)
|   command-execute(gnus-article-read-summary-keys)
`----

The problem is the %i in the template above.  This will include any
"description" found in the calendar invite, if there, but should be
nothing if not.  I am sure (but maybe I am wrong) that this capture
template used to work before.

In any case, if the initial contents are not defined, should this really
be an error?

org up to date from git as of a minute or two ago; emacs from git from a
couple of days ago.

Thank you.

PS - maybe it's gnus that is at fault here?
-- 
: Eric S Fraga via Emacs 28.0.50, Org release_9.3.6-345-g415083