Limit Essential Grid's WP_Query to only include Featured Events that have a featured image

functions.php

<?php
/**
 * Limit Essential Grid's WP_Query to only include Featured Events that have a featured image
 *
 * @link https://theeventscalendar.com/knowledgebase/featured-events/
 *
 * Based on https://gist.github.com/cliffordp/a6aad3c60f469970b1ecb209d85ec755
 * Similar code for Slider Revolution: https://gist.github.com/Camwyn/ce34677cafe52d46c12c11c8b9119371
 * Same Essential Grid code except without requirement for being a Featured Event (works for more than just The Events Calendar): https://gist.github.com/Camwyn/cc191bc1c95581c38f7ed5f8ba61da11
 *
 * essgrid_get_posts filter is from /wp-content/plugins/essential-grid/includes/base.class.php
 *
 * Tested working with version 6.5.24
 *
 * Filter hook only applies to Essential Grid > Source > Source Based on Posts, Pages, Custom Posts
 *
 * @return array
 */
function essgrid_post_based_featured_events_w_featured_image( $query, $grid_id ) {

	/* YOU MUST CHANGE THESE TO YOUR OWN SLIDER REVOLUTION SLIDER IDs!!! */
	$grid_ids_to_affect = array( 1, 2, 14 ); // include IDs of grids to affect

	// if this grid is not one to affect, do no filtering
	if ( ! in_array( $grid_id, $grid_ids_to_affect ) ) {
		return $query;
	}

	// get the existing meta_query so we aren't wiping that out
	if ( ! empty( $query['meta_query'] ) ) {
		$meta_query = (array) $query[ 'meta_query' ];
	} else {
		$meta_query = [];
	}

	// do the filtering...

	// has a Featured Image
	$meta_query[] = array(
		'compare' => 'BETWEEN',
		'key' => '_thumbnail_id',
		'value'   => [ 1, PHP_INT_MAX ],
	);

	// Restrict to events(posts) that have are featured events.
	if ( class_exists( 'Tribe__Events__Main' )
	     && class_exists( 'Tribe__Events__Featured_Events' )
	     && in_array( Tribe__Events__Main::POSTTYPE, (array) $query['post_type'] )
	) {
		$meta_query[] = [
			'compare' => 'EXISTS',
			'key'     => Tribe__Events__Featured_Events::FEATURED_EVENT_KEY,
		];
	}

	$query['meta_query'] = $meta_query;

	return $query;
}

add_filter( 'essgrid_get_posts', 'essgrid_post_based_featured_events_w_featured_image', 10, 2 );