ACF Post Object field and WPML (show posts of both languages => disabling filtering)

functions.php

<?php

/* Customize the ACF Post Object queries, so they return posts in both languages */
function customize_acf_query( $args, $field, $post )
{
	if($field['type']=='post_object'){
		$args['orderby'] = 'title';
		$args['suppress_filters'] = true; // Suppress filters so WPML doesn't filter to only 1 lang
		return $args;
	}
}

// add filter function
add_filter('acf/fields/post_object/query', 'customize_acf_query', 10, 3);

Since the filter only applies to the post_object field, checking the $field['type'] is redundant.