Show all scheduled events OR corn jobs in WordPress. Use this snippet for only debugging purpose.

show-all-scheduled-events.php

<?php
/**
 * Show all scheduled events OR corn jobs.
 *
 * NOTE: Use this snippet for only debugging purpose.
 * 
 * @todo Change the `prefix_` and with your own unique prefix.
 * 
 * @since 1.0.0
 */
if( ! function_exists( 'prefix_show_all_scheduled_events' ) ) :
	function prefix_show_all_scheduled_events() {
		echo "<pre>";
		print_r( wp_get_schedules() );
		echo "</pre>";
		wp_die( );
   }
   add_action( 'admin_head', 'prefix_show_all_scheduled_events' );
endif;