Wordpress custom field sorting, weird behavior: the latest post is at the end

Question

I am using Wordpress with Advanced Custom Fields. I have a custom post called "event" with a custom field "date" (I have added the field through ACF). The date field is formatted in the following way: "yyyy-mm-dd." Until now, sorting the custom posts worked fine using the following snippet:

$query = new WP_Query([
    'post_type' => 'event',
    'meta_key' => 'tq_event_date',
    'meta_value' => date('Y-m-d'),
    'meta_compare' => '<',
    'orderby' => ['meta_key' => 'tq_event_date'],
    'posts_per_page' => '-1'
]);

if($query->have_posts()) {
    $posts = $query->get_posts();
    foreach($posts as $post) {
        echo get_field('tq_event_date', $post->ID). ' ';
    }
}

Now I have added a new event post with date "2015-12-03." The sorting for some reason does not sort this post. Here are the results of this query:

2015-08-15
2015-07-15
2015-06-02
2015-05-18
2015-04-21
2015-04-18
2015-04-17
2015-04-02
2015-03-28
2014-11-25
2014-07-14
2014-07-04
2014-06-08
2014-05-31
2014-04-25
2014-04-26
2014-03-14
2014-03-15
2014-02-23
2014-02-23
2013-12-16
2013-11-19
2013-11-12
2013-07-24
2013-06-09
2013-05-12
2013-04-26
2013-04-19
2013-04-10
2013-04-05
2012-12-08
2012-11-02
2012-10-22
2012-10-09
2012-10-07
2012-06-23
2012-03-07
2012-02-12
2012-02-07
2011-06-18
2011-05-26
2011-04-30
2011-04-06
2011-02-26
2011-02-11
2011-01-28
2010-12-28
2010-11-22
2010-10-30
2010-10-16
2010-09-16
2010-05-29
2010-05-05
2010-03-29
2010-03-23
2015-12-03

For some reason, the last post is the one that I just added. I really cannot find the reason for this problem's existence... What am I doing wrong?

EDIT: Changed the custom field from date to tq_event_date but still didn't work.

Answer 1

The line:

'orderby' => ['meta_key' => 'tq_event_date']

didn't work. So, based on my context, where all the dates start with a number, I was able to sort the items in the following way:

'orderby' => 'meta_value'

If in the future something changes, I think the best way to solve the problem is doing it in PHP:

usort($posts, function($a, $b) {
    $d1 = get_field('tq_event_date', $a);
    $d2 = get_field('tq_event_date', $b);
    return strcmp($d2, $d1);
});

Answer 2

The problem might be that you don't specify the type of meta_query which is alphabetical by default and might mess up numberic queries as stated in WP_Query codex.

Try this:

//Note how:

   //1. meta_query is also array 
   //2. I specify that meta_value is numeric and type is date

$event_args = array(
            'post_type'         => 'event',
            'posts_per_page'    => -1,
            'meta_query'        => array(
                                       array(
                                           'key'            => 'tq_event_date',
                                           'meta_value_num' => date(Y-m-d),
                                           'type'           => 'DATE', //You can also try 'NUMERIC'
                                           'compare'        => '<',
                                       )
                                   ),
            'orderby' => 'meta_value',
);

$events = new WP_Query( $event_args );

//etc