[Resolved] Hidden languages are showing up in the AIOSEO sitemap

Yes sure I would be happy to help. I will only work on this particular file to add the fix and will not touch anything else in your site:
/wp-content/plugins/all-in-one-seo-pack/app/Common/Sitemap/Localization.php

1. === Please create a Full backup of your website ===

2. Please provide temporary access (WP-Admin and FTP Login info) to your site.

Your next answer will be private which means only you and I have access to it.

Thank you, have a great weekend.

Could you please take a backup of your site and follow the below steps:

1. Please make sure to download and install the latest version of the AIOSEO plugin so that it will remove the previous changes.

2. Go to: wp-content/plugins/all-in-one-seo-pack/app/Common/Sitemap/Localization.php file.

2.1. Replace the below code:

	public function localizeEntry( $entry, $entryId, $objectName, $objectType ) {
		$translationGroupId = apply_filters( 'wpml_element_trid', null, $entryId );
		$translations       = apply_filters( 'wpml_get_element_translations', null, $translationGroupId, $objectName );

With:

public function localizeEntry( $entry, $entryId, $objectName, $objectType ) {
		$translationGroupId = apply_filters( 'wpml_element_trid', null, $entryId );
		$translations       = apply_filters( 'wpml_get_element_translations', null, $translationGroupId, $objectName );
		$hiddenLanguages = apply_filters( 'wpml_setting', [], 'hidden_languages' );
        foreach ($hiddenLanguages as $language){
            if ($translations[$language]) {
                unset ($translations[$language]);
            }
        }

3. Go to: wp-content/plugins/all-in-one-seo-pack/app/Common/Sitemap/Query.php file.

3.1. Replace the below code:

public function posts( $postTypes, $additionalArgs = [] ) {

With:

public function posts( $postTypes, $additionalArgs = [] ) {
		global $wpdb;

3.2. Replace the below code:

$excludedPosts = aioseo()->sitemap->helpers->excludedPosts();

With:

$excludedPosts = aioseo()->sitemap->helpers->excludedPosts();
$hiddenLanguages = apply_filters( 'wpml_setting', [], 'hidden_languages' );
foreach ($hiddenLanguages as $langage){
        $excludedPosts .= implode(',',$wpdb->get_col("SELECT `element_id` FROM `{$wpdb->prefix}icl_translations` WHERE `element_type` = 'post_$postTypes' AND `language_code` LIKE '$langage'"));
        }

I have just tested at the fresh WP site and it seems to be working correctly as you can see on this page:
hidden link

You may copy the updated code from the above site. Here is the auto login URL of that fresh WP site: hidden link

If you find any issues in applying these changes to your site, please let me know and I’ll be happy to apply these changes to your site.

Please let me know if this resolves your issue or if you need further assistance.

Thank you for your cooperation and patience

Sorry for the delay, it was my weekend (Friday-Saturday). I have tried to reproduce this issue at your test site by following the below steps:

1. Deleted the existing AIOSEO plugin.
2. Downloaded the modified version from our sandbox site.
3. Installed/activated the modified version on your test site.
4. Removed the Chinses Traditional language from the WPML >> Languages > hidden languages list.

It seems it's working correctly at your site as you can see in this link:
hidden link

Please let me know if I missed something or please make sure you have followed the same steps on your live site as I shared above.

Looking forward,
Thank you

It turns out that this compatibility issue is more complex than we initially thought. We identified that its a problem in AIOSEO plugin code so we will need their developers to provide to the actual code fix for this issue. We tried to provide a workaround which is not an actual fix that is why we are facing these odd issues with Custom post types etc.

In the meantime we suggest to Remove any language from WPML settings that you do not need, to avoid it to be shown in sitemap - the languages that you are currently hiding. I have informed our compatibility team with latest results and they will be working out with the AIOSEO developers to offer a better fix for this issue but it will take time as this depends on how fast AIOSEO team responds to our requests & provides the actual fix in their plugin.

Thanks