WordPress ajax filter returning all posts when it should be filtering by category

Here is My code, it should be filtering by category, it displays all posts on any checkbox I click, I don’t know how to fix this, I have tried everything.

<form id="filter">
    <?php
        if( $terms = get_terms( 'category', 'orderby=name' ) ) : // to make it simple I use default categories
        foreach ( $terms as $term ) :
            echo '<input type="checkbox" name="category[]" value="' . $term->term_id . '" class="br">' . $term->name;
            echo '';
        endforeach;
        endif;
    ?>
    <div class="filter-output"></div>
</form>

Here is the js (coded inside a template page)

jQuery('#filter .br').click(function(){

    // Declaratie van array
    var choices = {};

    jQuery('.contents').remove();
    jQuery('.filter-output').empty();

    jQuery('input[type=checkbox]:checked').each(function() {
        if (!choices.hasOwnProperty(this.name)) 
            choices[this.name] = [this.value];
        else 
            choices[this.name].push(this.value);
    });


    console.log(choices);
    jQuery.ajax({
        url: '<?php echo admin_url('admin-ajax.php'); ?>',
        type :'POST',
        data : {
            'action' : 'call_post', // Naam van de PHP functie
            'choices' : choices,
        },
        success: function (result) {
            jQuery('.filter-output').append(result);
            // Voor testen - Resultaat (Kan later verwijderd worden)
            //console.log(Resultaat);
            //console.log(Keuzes);
        },
        error: function(err){
            // Voor testen - Error (Kan later verwijderd worden)
            console.log(err);
            console.log(choices);
        }
    });
})

funstions.php

add_action('wp_ajax_call_post', 'call_post');
add_action('wp_ajax_nopriv_call_post', 'call_post');

function call_post(){

// Verkijgen van AJAX data:
$choices = $_POST['choices'];


$meta_query = array('relation' => 'OR');
foreach($choices as $Key=>$Value){

    if(count($Value)){
        foreach ($Value as $Inkey => $Invalue) {
            $meta_query[] = array( 'key' => $Key, 'value' => $Invalue, 'compare' => '=' );
        }
    }
}
$args = array(
    'post_type' => 'post',
    'meta_query' =>$meta_query
);

$query = new WP_Query($args);
 //if( ! empty ($params['template'])) {
     ////$template = $params['template'];
     if( $query->have_posts() ) :
         while( $query->have_posts() ): $query->the_post();
             the_title();
         endwhile;
         wp_reset_query();
     else :
         wp_send_json($query->posts);
     endif;
 //}

die(); }

Anyone please help, I have been trying to make this work since yesterday and with no luck at all