Stores not loading

I’m using this plugin, with WPML, but the plugin is not loading the stores,

GET/wp-admin/admin-ajax.php?action=asl_load_stores&nonce=401e7e2166&lang=&load_all=1&layout=1 500 (Internal Server Error) jquery.min.js?ver=3.7.1:2

above there is the error, when i access

/wp-admin/admin-ajax.php?action=asl_load_stores&nonce=401e7e2166&lang=&load_all=1&layout=1 it throws the 500 error

This page isn’t working is currently unable to handle this request.
HTTP ERROR 500

if i change the url and add content to the lang parameter, for example:

/wp-admin/admin-ajax.php?action=asl_load_stores&nonce=401e7e2166&lang=en&load_all=1&layout=1

this will return the stores data

here are some examples i have tryed to solve this issue but none work:

[ASL_STORELOCATOR lang=”EN”], [ASL_STORELOCATOR lang=”en_GB”],

function custom_asl_storelocator_shortcode_with_wpml()
{
    $current_lang = apply_filters('wpml_current_language', null);
    if ($current_lang == 'es') {
        $current_lang = 'es';
    } elseif ($current_lang == 'en') {
        $current_lang = 'en';
    } else {
        $current_lang = 'pt-pt';
    }
    return do_shortcode('[ASL_STORELOCATOR lang="' . esc_attr($current_lang) . '"]');
}

add_shortcode('custom_storelocator', 'custom_asl_storelocator_shortcode_with_wpml');

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