[display-posts post_type="ai1ec_event"]

functions.php

<?php

/**
 * Display Posts - All in One Event Calendar 
 * @see https://wordpress.org/support/topic/support-for-all-in-one-event-calendar/
 *
 * @param array $args, query arguments
 * @param array $atts, shortcode attributes
 * @return array $args, modified query arguments 
 */
function be_dps_ai1ec( $args, $atts ) {
	if( empty( $args['post_type'] ) || 'ai1ec_event' !== $args['post_type'] )
		return $args;
    
	// This function is in the plugin. If it can't be found, plugin isn't active so return early
	if( ! function_exists( 'ai1ec_return_false' ) )
		return $args;
    
	global $ai1ec_calendar_helper, $ai1ec_events_helper;

	// gets localized time
	$bits = $ai1ec_events_helper->gmgetdate( $ai1ec_events_helper->gmt_to_local( time() ) );

	//sets start time to today
	$start = gmmktime(0,0,0,$bits['mon'],$bits['mday'],$bits['year']);

	//sets end time to a year from today i.e. $bits['year']+1
	$end = gmmktime(0,0,0,$bits['mon'],$bits['mday'],$bits['year']+1);

	//Look in class-ai1ec-calendar-helper.php for details
	$get_events = $ai1ec_calendar_helper->get_events_between($start,$end);
    
	foreach($get_events as $event ):
		$post_ids[] = $event->post_id;
	endforeach;

	$args['post__in'] = $post_ids;
	$args['orderby'] = 'post__in';
	return $args;
    
}
add_filter( 'display_posts_shortcode_args', 'be_dps_ai1ec', 10, 2 );