Thank you very much, MrFale67. I fixed this problem by setting the
"Preserver scripting changes to form when saved" to "Manually" and then
clicked OK, then saved the PDF, then went back into Properties and
changed it back to "Automatically" after which it started working as
expected. I'm not sure how/when the setting got out of sync with the
display, but changing it then back again seems to have fixed it. Thank
you for your assistance!