Pagination, second page blank?

I have category-exhibitions.php where I am looping the exhibitions category and now I need the pagination part.

<?php
            $paged = ( get_query_var( 'paged' ) ) ? get_query_var( 'paged' ) : 1;
            $args = array( 'cat' => 6, 'posts_per_page' => 2, 'paged' => $paged );
            $loop = new WP_Query( $args );
            while ( $loop->have_posts() ) : $loop->the_post();
            ?>
            <div class="news">
                <div class="small-title"><?php echo get_cat_name(6) ?></div>
                <div class="main-title"><?php the_title(); ?></div>
                <div class="details">
                    <p>
                        <?php the_excerpt(); ?>
                    </p>
                </div>
                <div class="posted-datetime"><strong>POSTED ON:</strong> <?php the_time( get_option( 'date_format' ) ); ?>  <a href="<?php the_permalink() ?>">READ MORE <i id="arrow" class="fa fa-angle-right"></i></a></div>
                <div class="red-gray-line" style="width:76%;margin-bottom:5%;">
                    <div class="red-line"></div>
                    <div class="gray-line" style="width:82%;"></div>
                </div>
            </div>

            <?php

            endwhile;

            ?>
<?php
                    $big = 999999999; // need an unlikely integer

                    echo paginate_links( array(
                        'base' => str_replace( $big, '%#%', esc_url( get_pagenum_link( $big ) ) ),
                        'format' => '?paged=%#%',
                        'current' => max( 1, get_query_var('paged') ),
                        'total' => $loop->max_num_pages
                    ) );
                    ?>

the pagination appears, unfortunately the second page is blank.
any suggestion or help?