Hello Michael,

>>>>> Michael Eliachevitch <m.eliachevitch@posteo.de> writes:

    > Hello Colin,
    >> This is amazing. I have run into exactly the same problem. I was
    >> wondering whether to report it!
    >> 
    >> Oh, and I can reproduce the bug with your ECM.

    > Glad that I'm not alone. When you say you ran into this, is this
    > something that appeared to you in a recent org-version for
    > existing capture templates which worked in older versions? Or is
    > this a behavior that has been always there for capture-templates
    > with :clock-in?

A couple of night ago, I thought I'd try experimenting with my
org-capture setup. I normally have a menu with single letter choices and
no hierarchy. I wrote a couple of lines, very similar to yours, but
couldn't get it to work. I thought it simply indicative of my ignorance
of lisp (which is profound!) and abandoned the experiment. I use org-mode
version 9.5.1 and I got the same results with emacs-28.0.90, 29.0.50 and
(I think) 27.2.

    > When I have time I might try if I can hack something to fix this,
    > but not sure if I have time as I'm quite busy with my PhD
    > currently. Btw, I'm not sure what the procedure following the bug
    > report will be, as I'm quite new here on the mailing list and am
    > still more used to working with github-issues etc, but I guess
    > patience is key in an open source project.

If you get no response on this org-mode list, perhaps re-submit it as a
normal emacs bug (M-x report-emacs-bug <RET>).

Best wishes,

Colin.