Infinity scroll repeating initial posts

I am trying to use infinity scroll and for some reason it is repeating the initial set of posts and when I reach the end it is jumping back up and repeating the same thing again, causing an erratic scrolling behaviour. I have a custom query which is ordering the posts by a field (added by ACF) called event_date.

I am adding infinity scroll support to my theme as follows:

function infinite_scroll_init() {
	add_theme_support( 'infinite-scroll', array(
			'container' => 'events',
			'footer' => false,
			'footer_widgets' => false,
			'posts_per_page' => get_option('posts_per_page'),
			'render' => 'infinite_scroll_render',
	) );
}
add_action( 'after_setup_theme', 'infinite_scroll_init');

function infinite_scroll_render() {
	get_template_part( 'content','posts' );
}

function jetpack_infinite_scroll_query_args( $args ) {
	$args['order']   = 'DESC';
	$args['meta_key'] = 'event_date';
        $args['orderby'] = 'meta_value';
	return $args;
}
add_filter( 'infinite_scroll_query_args', 'jetpack_infinite_scroll_query_args' );

My content-posts.php looks like this (it is also being included from index.php with get_template_part().

$paged = get_query_var( 'paged' ) ? get_query_var( 'paged' ) : 1;
$posts_per_page = (isset($posts_per_page)) ? $posts_per_page : get_option('posts_per_page');

$args = array(
    'post_type' => 'post',
    'meta_key' => 'event_date',
    'orderby' => 'meta_value date',
    'order' => 'DESC',
    'posts_per_page' => $posts_per_page,
    'paged' => $paged
);

$date_format = "jS F Y";

$query = new WP_Query( $args );
if ($query->have_posts()) : ?>
   <?php  $index = 0; ?>
    <?php while ( $query->have_posts() ) : $query->the_post(); ?>

     <?php $event_date = get_field('event_date');
        if ($event_date) {
            $event_date = date_i18n($date_format, strtotime($event_date));
        } else { //fallback which shouldn't really happen, event_date is compulsory
            $event_date = get_the_date($date_format);
        } ?>

       <?php $thumbnail_url = wp_get_attachment_image_src(get_post_thumbnail_id(get_the_ID()), 'large' )[0]; ?>
        <a class="news" style="background:url(<?php echo $thumbnail_url; ?>) no-repeat center center;" href="<?php the_permalink(); ?>">
            <span class="caption"><h1><?php the_title(); ?></h1><h2>- <?php echo $event_date; ?> -</h2></span>
        </a>

        <?php if ($index % 3 == 3) : ?></div><?php endif; ?>
        <?php $index++; ?>
      <?php endwhile; // end of the loop. ?>

      <?php if ($index % 3 != 3) : ?></div><?php endif; ?>

<?php endif; ?>
<?php wp_reset_query(); ?>

It seems like it has something to do with the $paged variable, but can’t figure how to go around this. What can I do to get this to work properly?

https://ww.wp.xz.cn/plugins/jetpack/