Sorry for taking so long to follow up! I got most of the way there. I put the short code in the header element for the child theme. Using a child theme for activello, I updated content-page.php line 14 to read:
<h1 class="entry-title"><?php
echo do_shortcode('[issuem_issue_title]');
?>
</h1>
That put the correct heading everywhere except the archive page, and stand alone pages that exist outside the template (Submit Articles/About/etc.) Any tips on how to address that? Is there a better place to put the issuem shortcode?
In the meantime I changed the template to read:
<h1 class="entry-title"><?php the_title(); ?><?php
echo do_shortcode('[issuem_issue_title]');
?></h1>
to list both the current issue and the page heading, as a temporary work-around.
