Can’t get it to work

<div class="nemovitost-galerie">
    <div class="nemovitost-galerie__featured">
        <?php
        $featured_full = get_the_post_thumbnail_url( $property, 'full' );
        $featured_large = get_the_post_thumbnail_url( $property, 'medium_large' );
        $image_caption = get_post(get_post_thumbnail_id())->post_excerpt; // Get image caption for PhotoSwipe
        ?>
        
        <a href="<?php echo $featured_full; ?>" data-size="1600x1067" data-pswp-uid="1" data-lbwps-gid="gallery-1"> <!-- Added data-lbwps-gid -->
            <img src="<?php echo $featured_large; ?>" alt="<?php echo esc_attr( get_the_title() ); ?>">
        </a>
    </div>
    
    <div class="nemovitost-galerie__thumbs">
        <?php
        $counter = 1; // Start counter for image UIDs
        foreach( $property->fotografie as $attach_id => $foto ) {
            if( $attach_id == get_post_thumbnail_id( $property->ID ) ) continue; // Skip featured photo
            
            $counter++;
            $size = $foto['medium'];
            $url = $size[0];
            $large_image_url = wp_get_attachment_image_src( $attach_id, 'full' );
            ?>
            
            <a href="<?php echo $large_image_url[0]; ?>" class="nemovitost-galerie__thumb <?php echo $counter > 9 ? 'nineplus' : ''; ?>" data-pswp-uid="<?php echo $counter; ?>" data-lbwps-gid="gallery-1"> <!-- Added data-lbwps-gid -->
                <img src="<?php echo $url; ?>" alt="<?php echo esc_attr($property->post_title); ?>" />
            </a>

            <?php
        }
        ?>
    </div>
</div>

I’m sorry, but I can not really help here. The result of this code should be ok – but it may be, that this code runs after the output buffer for the current request was already handled. I could not tell it without having a look to the complete website installation and a debugger for it. But this is out of scope in this support forum, sorry.

I understand. I’ll try dig into it and not break it any more.
One of the pages with the gallery is:
https://www.bohunekvankova-reality.cz/nemovitost/prodej-bytu-31-81-m2-pohled/

Your problem is not the HTML code. You use some kind of “JavaScript optimizer”. Don’t do this – or if possible exclude Lightbox with PhotoSwipe from it.

Modular JavaScript (which PhotoSwipe uses for good reasons) will usually get damaged by “optimizers” and using these optimizers nowadays is mostly useless, since HTTP/2 (which your website uses as well) uses methods to avoid additional turnarounds when requesting many single resources. So it makes no big difference if you have 1 or 20 JavaScript files to load since all will be loaded with only one single connection which gets reused until all resources got loaded for the current URL.

And for the future: if you experience any problems – disable ALL caching and ALL “optimizer” first! Only then you will see, if there is any issue with your code and not just a side effect caused by any caching or optimizing plugins.

• This reply was modified 3 weeks, 5 days ago by Arno Welzel.

Thank you for Your advice. I’ll investigate.