Hi all, please let me know if the attached minimal example doesn't
come through for whatever reason.

It looks like (org-agenda-to-appt) displays a todo item on its
deadline date at the scheduled time, if the scheduled and deadline
dates are different (and the deadline has no time).  The expected
behavior is to not consider the deadline an appointment at a
particular time at all (because it has none specified).

Thanks for your time,
Nick