wpdsbarnes

Thank you so much! I had myself in a … loop (had to).

Basically one just needs to say, if this category has children, links pls,
otherwise, normal archive page.

In the child theme I copied the contents of “archive.php” to “category.php” (So, archive.php will be a show all page) which looks like this for the next person that wonders:

<?php
/**
 * The template for displaying archive pages
 *
 * @link https://developer.ww.wp.xz.cn/themes/basics/template-hierarchy/
 *
 * @package WordPress
 * @subpackage Twenty_Twenty_One
 * @since Twenty Twenty-One 1.0
 */

get_header();
$description = get_the_archive_description();
?>

<?php if ( have_posts() ) : ?>
	<header class="page-header alignwide">
		<?php the_archive_title( '<h1 class="page-title">', '</h1>' ); ?>
		<?php if ( $description ) : ?> <div class="archive-description"><?php echo wp_kses_post( wpautop( $description ) ); ?></div> <?php endif; ?>
	</header><!-- .page-header -->

	<?php $category_id = get_query_var( 'cat' ); ?>
	<?php $parent_categories = get_categories( array('child_of' => $category_id) ); ?>
	
	<div class="entry-content">
		<?php foreach($parent_categories as $category) { 
		//  echo title of the subcategory as a link
			echo '<p> <a href="' . get_category_link( $category->term_id ) .  '" title="' . sprintf( __( "View all posts in %s" ), $category->name ) . '" ' . '>' .  $category->name.'</a> </p>';
		} ?>
	</div>

	<?php if( ! $parent_categories ){
		while ( have_posts() ) : 
			the_post();
			get_template_part( 'template-parts/content/content', get_theme_mod( 'display_excerpt_or_full_post', 'excerpt' ) );
		endwhile;
	} ?>

<?php else : ?>
	<?php get_template_part( 'template-parts/content/content-none' ); ?>
<?php endif; ?>

<?php get_footer(); ?>

Resolved

I believe I’ve isolated the issue down to the child theme folder being named with a number “1988”.

When I change the name to “nineteeneightyeight” the featured image appears again as an option.

Sorry If I’ve missed it, but is there documentation about what is and is not a valid theme name?

Since the featured image option has reappeared, and that was the original issue, I’ll mark this as resolved.

@diondesigns & @aetherunbound

you’re both awesome!
I’d stopped putting the paths into file_get_contents() at some point (and apparently was checking if a string was a file).

Thank you both so much for the response!

Resolved.