sorry, the snippet above is the wrong one, I do not use the filter, I use @ismael modification here:
https://kriesi.at/support/topic/masonry-blog-show-category-name-without-filter-but-directly-in-theme-file/#post-1036902

/* show category name in ALB element "blog masonry" */				
$categories = get_the_category($entry['ID']);
				$separator = ' | ';
				$count = count($categories);
				$i = 0;
				$output_cat = "<div class='masonry-categories'>";
				if ( ! empty( $categories ) ) {
					foreach( $categories as $category ) {
						if($i++ === $count) {
							$separator = '';
						}
						$output_cat .= '<span alt="' . esc_attr( sprintf( __( 'View all posts in %s', 'textdomain' ), $category->name ) ) . '">' . esc_html( $category->name ) . '</span>' . $separator;
					}
				}
				$output_cat .= "</div>";

				$cat = trim( $output_cat, $separator );

				$text_before .= $cat;

@Rikard

I do not use any token – I do everything fully manual via FTP.
I have marked the notification in my ENVATO account for theme updates.

It works fine, thank you very, very much, Ismael. I appreciate your time and efforts very much!

Please refer to my first post:
Your suggested plugin is not what I’d like to achieve.
And I already have a tutorial and code snippets – see above, but not sure,

– how to put it into an ENFOLD “function” and
– where to place the HTML part exactly in the comments.php

I work within the theme files, it is easier for me and my bad PHP knowledge, and it is easier for me with further tweaks of this styling – that’s my way to work.

So I placed your snippet as asked into av-helper-masonry.php around line 539 in this context:

				$this->loop[$key]['text_before']	= "";
				$this->loop[$key]['text_after']		= "";
				$this->loop[$key]['ID'] = $id		= $entry->ID;
				$this->loop[$key]['post_type'] 		= $entry->post_type;
				$this->loop[$key]['thumb_ID'] 		= get_post_thumbnail_id($id);
				
				$post_categories = wp_get_post_categories( 4 );
				$categories = get_the_category($post_categories[0]);
													
				$this->loop[$key]['the_title'] 		= get_the_title($id);
				$this->loop[$key]['url']			= get_permalink($id);
				$this->loop[$key]['date'] 			= "<span class='av-masonry-date meta-color updated'>".get_the_time($date_format, $id)."</span>";
				$this->loop[$key]['author'] 		= "<span class='av-masonry-author meta-color vcard author'><span class='fn'>". __('by','avia_framework') .' '. $author."</span></span>";
				$this->loop[$key]['class'] 			= get_post_class("av-masonry-entry isotope-item", $id); 
				$this->loop[$key]['content']		= strip_tags( $entry->post_excerpt );
                $this->loop[$key]['description']	= !empty($entry->post_content) ? $entry->post_content : $entry->post_excerpt;
				

and this output no category name above the title:

View post on imgur.com

Please test it at your demo installation, my site is not yet online. Thanks.

I still haven’t made any changes to any file in ENFOLD.
I only tried this snippet in the my Code-Snippets-Plugin (which holds every snippet that normally goes to the function.php):

add_filter('avf_loop_index_blog_meta', 'avf_loop_index_blog_meta_mod', 10, 1);
function avf_loop_index_blog_meta_mod($output) {
	$link = get_permalink();
	$fallback = strpos($output, 'iconfont');

	if ($fallback <= 200) {
	    $output = "<a href='{$link}' class='small-preview' title='Advanced Post'><img src='FALLBACK IMAGE URL HERE'/></a>";
	}

	return $output;
}

But probably that is not the right snippet or it is not complete, so that also at the search results page this default fallback image appears.