Custom get_the_excerpt() only works on first post

Question

I use a custom get_the_excerpt function in my theme. It works perfectly for the first post in the loop, but the other posts are using the standard excerpt function. I do not understand why?

The custom get_the_excerpt function:

function wpse_allowedtags() {
    // Add custom tags to this string
    return '<br>,<b>,<strong>,<em>,<i>,<ul>,<ol>,<li>,<a>,<p>,<h2>,<h3>,<h4>,<h5>'; 
}

remove_filter('get_the_excerpt', 'wp_trim_excerpt');
add_filter('get_the_excerpt', function($wpse_excerpt) {
    $raw_excerpt = $wpse_excerpt;

    if ( '' == $wpse_excerpt ) {
        $wpse_excerpt = get_the_content('');
        $wpse_excerpt = strip_shortcodes( $wpse_excerpt );
        $wpse_excerpt = apply_filters('the_content', $wpse_excerpt);
        $wpse_excerpt = str_replace(']]>', ']]&gt;', $wpse_excerpt);
        $wpse_excerpt = strip_tags($wpse_excerpt, wpse_allowedtags()); 

        $excerpt_word_count = 150;
        $excerpt_length = apply_filters('excerpt_length', $excerpt_word_count); 
        $tokens = array();
        $excerptOutput = '';
        $count = 0;

        // Divide the string into tokens; HTML tags, or words, followed by any whitespace
        preg_match_all('/(<[^>]+>|[^<>\s]+)\s*/u', $wpse_excerpt, $tokens);

        foreach ($tokens[0] as $token) { 
            if ($count >= $excerpt_length && preg_match('/[\,\;\?\.\!]\s*$/uS', $token)) { 
                // Limit reached, continue until , ; ? . or ! occur at the end
                $excerptOutput .= trim($token);
                break;
            }

            // Add words to complete sentence
            $count++;

            // Append what's left of the token
            $excerptOutput .= $token;
        }

        $wpse_excerpt = trim(force_balance_tags($excerptOutput));

        $excerpt_end = '&nbsp;…&nbsp;<a href="'. esc_url( get_permalink() ) . '">' 
                . __('[ weiterlesen ]', 'jankosyk') . '</a>'; 
        $excerpt_more = apply_filters('excerpt_more', ' ' . $excerpt_end); 

        $pos = strrpos($wpse_excerpt, '</');
        if ($pos !== false) {
            // Inside last HTML tag
            $wpse_excerpt = substr_replace($wpse_excerpt, $excerpt_end, $pos, 0); // Add read more next to last word 
        } else {
            // After the content
            $wpse_excerpt .= $excerpt_more; // Add read more in new paragraph 
        }

        return $wpse_excerpt;   

    }
    return apply_filters('wpse_custom_wp_trim_excerpt', $wpse_excerpt, $raw_excerpt);
});

The loop:

<?php if (have_posts()) : while (have_posts()) : the_post(); ?>
    <div class="entry"><?php
        if(is_single() || is_page()) {
            ?><h2><?php the_title(); ?></h2><?php
            the_content();
        } else { ?>
            <h2><a href="<?php the_permalink() ?>"><?php
                the_title(); 
            ?></a></h2><?php
            print get_the_excerpt();
        }  
    ?></div><?php
endwhile; ?>

The website can be found here: https://jankosyk.de/

Any suggestions?

Thanks!

---

Update:

As I do not use the excerpt from the post edit screen and just want to shorten the post text I ended up with the following function completely ignoring every automatically generated excerpt:

function wpse_allowedtags() {
    // Add custom tags to this string
    return '<br>,<b>,<strong>,<em>,<i>,<ul>,<ol>,<li>,<a>,<p>,<h2>,<h3>,<h4>,<h5>'; 
}
remove_filter('get_the_excerpt', 'wp_trim_excerpt');
add_filter('get_the_excerpt', function() {
    $wpse_excerpt = get_the_content('');
    $wpse_excerpt = strip_shortcodes( $wpse_excerpt );
    $wpse_excerpt = apply_filters('the_content', $wpse_excerpt);
    $wpse_excerpt = str_replace(']]>', ']]&gt;', $wpse_excerpt);
    $wpse_excerpt = strip_tags($wpse_excerpt, wpse_allowedtags()); 

    $excerpt_word_count = 150;
    $excerpt_length = apply_filters('excerpt_length', $excerpt_word_count); 
    $tokens = array();
    $excerptOutput = '';
    $count = 0;

    // Divide the string into tokens; HTML tags, or words, followed by any whitespace
    preg_match_all('/(<[^>]+>|[^<>\s]+)\s*/u', $wpse_excerpt, $tokens);

    foreach ($tokens[0] as $token) { 
        if ($count >= $excerpt_length && preg_match('/[\,\;\?\.\!]\s*$/uS', $token)) { 
            // Limit reached, continue until , ; ? . or ! occur at the end
            $excerptOutput .= trim($token);
            break;
        }

        // Add words to complete sentence
        $count++;

        // Append what's left of the token
        $excerptOutput .= $token;
    }

    $wpse_excerpt = trim(force_balance_tags($excerptOutput));

    $excerpt_end = '&nbsp;…&nbsp;<a href="'. esc_url( get_permalink() ) . '">' 
            . __('[ weiterlesen ]', 'jankosyk') . '</a>'; 
    $excerpt_more = apply_filters('excerpt_more', ' ' . $excerpt_end); 

    $pos = strrpos($wpse_excerpt, '</');
    if ($pos !== false) {
        // Inside last HTML tag
        $wpse_excerpt = substr_replace($wpse_excerpt, $excerpt_end, $pos, 0); // Add read more next to last word 
    } else {
        // After the content
        $wpse_excerpt .= $excerpt_more; // Add read more in new paragraph 
    }

    return $wpse_excerpt;   
});

Answer 1

One possibility would be to simply write your custom filter to run later than the default priority of "10" (which is what the "wp_trim_excerpt" function is running at).

The get_the_excerpt filter passes the excerpt AND the post object. So you should be able to run your filter at a later priority and use the excerpt value from the post object instead of the passed excerpt, since that has already gone through another filter.

I changed your original from the anonymous function as you had it just for clarity on the priority and argument values.

// Running this filter at priority 20 so it comes later than wp_trim_excerpt()
add_filter( 'get_the_excerpt', 'my_later_excerpt', 20, 2 );
function my_later_excerpt( $possibly_filtered_excerpt , $post_obj ) {

    /*
     * Rather than change every instance of $wpse_excerpt in your
     * function, I changed the argument to $possibly_filtered_excerpt
     * and ignored it. Then set the $wpse_excerpt value to the 
     * excerpt contained in the post object ($post_obj->post_excerpt)
     */
    $wpse_excerpt = $post_obj->post_excerpt;

    $raw_excerpt = $wpse_excerpt;

    if ( '' == $wpse_excerpt ) {
        $wpse_excerpt = get_the_content('');
        $wpse_excerpt = strip_shortcodes( $wpse_excerpt );
        $wpse_excerpt = apply_filters('the_content', $wpse_excerpt);
        $wpse_excerpt = str_replace(']]>', ']]>', $wpse_excerpt);
        $wpse_excerpt = strip_tags($wpse_excerpt, wpse_allowedtags()); 

        $excerpt_word_count = 150;
        $excerpt_length = apply_filters('excerpt_length', $excerpt_word_count); 
        $tokens = array();
        $excerptOutput = '';
        $count = 0;

        // Divide the string into tokens; HTML tags, or words, followed by any whitespace
        preg_match_all('/(<[^>]+>|[^<>\s]+)\s*/u', $wpse_excerpt, $tokens);

        foreach ($tokens[0] as $token) { 
            if ($count >= $excerpt_length && preg_match('/[\,\;\?\.\!]\s*$/uS', $token)) { 
                // Limit reached, continue until , ; ? . or ! occur at the end
                $excerptOutput .= trim($token);
                break;
            }

            // Add words to complete sentence
            $count++;

            // Append what's left of the token
            $excerptOutput .= $token;
        }

        $wpse_excerpt = trim(force_balance_tags($excerptOutput));

        $excerpt_end = '&nbsp;…&nbsp;<a href="'. esc_url( get_permalink() ) . '">' 
                . __('[ weiterlesen ]', 'jankosyk') . '</a>'; 
        $excerpt_more = apply_filters('excerpt_more', ' ' . $excerpt_end); 

        $pos = strrpos($wpse_excerpt, '</');
        if ($pos !== false) {
            // Inside last HTML tag
            $wpse_excerpt = substr_replace($wpse_excerpt, $excerpt_end, $pos, 0); // Add read more next to last word 
        } else {
            // After the content
            $wpse_excerpt .= $excerpt_more; // Add read more in new paragraph 
        }

        return $wpse_excerpt;   

    }
    return apply_filters('wpse_custom_wp_trim_excerpt', $wpse_excerpt, $raw_excerpt);
}