为什么php echo在Windows版本的Firefox中不起作用

my php code in wordpress site as follows:

<div id="contact-tel">
     <h2>Tel: <?php echo the_field('phone', 17); ?></h2>    <!-- Windows version firefox does not display echo-->
</div>

I noticed in windows version firefox (not sure the version number of FF) does not display the telephone number after Tel: word. It just show Tel:

if I add some words before echo then it displays, also i noticed, while page finishes loading, Tel number shows and then hide quickly.

site location

Does anybody have any idea ?

I think I know what is going on, as I've seen this before.

Do you happen to have Skype installed? This installs a Firefox plugin which tries to detect phone numbers on web pages and makes them clickable, but often fails. Try disabling this addon and your phone number will show.

Try to remove div and h2 tags and see if it displays. PHP works on the server side and has nothing to do with browser version.

I have been developing WordPress web site locally on Mac, and I have similar issue. But, for my part echo work well on all browser. Only on my function with get_posts() that can not work on Safari and Firefox.

In my case, I try to echo out the list of bloggers form my template part content-blogger.php to index.php.

<aside class="row som-blog-author" aria-labelledby="som-blog-authors">

<div class="col-md-4">
    <h2 id="som-blog-authors">
        Blogger
    </h2>
</div>
<div class="col-md-8">
    <?php get_search_form(); ?>
</div>


<ul class="col-xs-12 som-blog-authors-list">

    <?php

        $som_authors = som_get_cat_authors( 'blog' );

        foreach ($som_authors as &$som_author) :

            $blog_author_name  = get_userdata( $som_author )->display_name;
            $blog_author_url   = get_author_posts_url( $som_author );

            echo '
            <li class="col-sm-4 col-xs-6">
                <a href="' . $blog_author_url . '">' . $blog_author_name . '</a>
            </li>
            ';

        endforeach;

    ?>

</ul><!-- .som-blog-authors-list -->

</aside><!-- .som-blog-author -->

I used function som_get_cat_authors() to create array of author's ids and echo out in foreach loop above. This function also didn't work on Firefox and Safari. I used var_dump($som_authors); to check the variable but it return null. But on chrome, it work perfectly.

function som_get_cat_authors( $cat ) {

    if ( is_category( $cat ) ) {

        $args = array(
            'posts_per_page' => -1,
            'category_name'  => $cat,
            'orderby'        => 'author',
            'order'          => 'ASC',
        );

        $cat_posts = get_posts( $args );

        $user_posts = array();

        foreach( $cat_posts as &$cat_post ) {

            $user_posts[] = $cat_post->post_author;

        }

        $author_id_array = array_unique( $user_posts );

        return $author_id_array;

    }

}

ps. <?php get_search_form(); ?> show on three browsers