Galleries not loading in tabs

To start, you are outputting each gallery twice in each tab. Remove the second reference to remove the extra loading icon.

Because the tabs are hidden on load, the gallery cannot initialize. You need to attach to your tab events to initialize the gallery. Try adding this to your theme’s functions.php file:

add_action( 'wp_footer', 'tgm_envira_reload_on_tabs' );
function tgm_envira_reload_on_tabs() {

    ?>
    <script type="text/javascript">
    $('.jq-tabs').on('tabsactivate', function(e, ui){
        $('.envira-gallery-wrap').each(function(i, el){
            $('#' + $(this).attr('id')).isotope('reLayout');
        });
    });
    </script>
    <?php

}