ACF Pro: Gallery Field incompatible sort with WPML

Hello Guys,

I have a big problem with the gallery field when I using WPML, too.
On translated pages the Order of the Images is lost and it order instead from lowest to highest Post-ID.

I debug it down and that my Report (with example IDs).

1. Call Gallery Field:

$images = get_field('gallery_field'. $post_id);

Expected Behavior of the Array Post-Ids: 5, 4, 6, 9.
The resulted Array: 4, 5, 6, 9.

2. get_field uses acf_get_posts with post__in

The Method get_attachments uses following code:

	// get posts
	$posts = acf_get_posts(array(
		'post_type'	=> 'attachment',
		'post__in'	=> $post__in
	));

3. acf_get_posts call get_posts, which is modified by WPML

See: https://github.com/AdvancedCustomFields/acf/blob/master/includes/api/api-helpers.php#L1596

4. acf_get_posts Try to validate the Order

See: https://github.com/AdvancedCustomFields/acf/blob/master/includes/api/api-helpers.php#L1604

The $order Array Contains now only falses and with array_multisort the "right" order will be resetted to "from lowest to highest".

I hope you can find a fix for this :)

Best Regards
Sysix

Start in includes/api/api-helpers.php at the get_attachments and acf_get_posts paths referenced in the report, then reproduce the gallery lookup on a translated page with WPML. Compare the requested post IDs with the returned array and verify that the expected image order is preserved.