Wordpress og:image not working in whatsapp?

I had created a Wordpress news website. There are many sharing options implemented! I added WhatsApp and send the URL to WhatsApp and share to WhatsApp! The issue is, initially the post image is shown when I share the link in WhatsApp. But now the image is not showing while I share the link in WhatsApp! There are no issues while sharing on facebook! When I inspect the page source WordPress automatically gives og:image as the post feature image! But it does not show up in WhatsApp. But when I copy paste the same og:image to header.php I WordPress it works perfectly! Initially, I thought of the size problem while later I found out that size is as per the og:image meta tag standard.

Here i post the single.php code:

?php
/**
 * NewsGamer Theme
 *
 * Theme by: MipThemes
 * http://themes.mipdesign.com
 *
 * Our portfolio: http://themeforest.net/user/mip/portfolio
 * Thanks for using our theme!
 *
 */

// load header
get_header();

// Get Page properties
$mip_current_page   = new MipThemeFramework_Page();

// Update Post View
MipThemeFramework_Post_Views::update_post_views($post-ID);

// Load Custom post headers
get_template_part( 'elements/parts/post-header-'. $mip_current_page-page_template .'' );
?

    !-- start:post-info-bar --
    ?php if ($mip_current_page-enable_post_info_bar) get_template_part( 'elements/post-info-bar' ); ?
    !-- end:post-info-bar --

    !-- start:page content --
    div id="page-content" class="?php echo esc_attr($mip_current_page-page_template_class); ? clearfix"

        ?php
            //get sidebar
            if ( ($mip_current_page-page_sidebar_template == 'left-sidebar')(!wp_is_mobile()) ) get_sidebar();
        ?

        !-- start:main --
        div id="main" class="main article"
            !-- start:article post --
            article id="post-?php echo esc_attr($post-ID); ?" ?php post_class('article-post clearfix'); ? ?php echo MipThemeFramework_Util::get_item_scope( $mip_current_page-review_post ); ?
            ?php
                if (have_posts()) :
                    // Get Template
                    get_template_part( 'elements/'. $mip_current_page-page_template .'' );
                else :
                    // No Posts
                    esc_html_e('No posts.', 'newsgamer');
                endif;
            ?
            /article
            !-- end:article post --
        /div
        !-- end:main --

        ?php
            //get sidebar
            if ( ($mip_current_page-page_sidebar_template == 'right-sidebar')||( ($mip_current_page-page_sidebar_template == 'left-sidebar')(wp_is_mobile()) ) ) get_sidebar();
        ?

    /div
    !-- end:page content --

?php
    // load footer
    get_footer();
?