我想在三列中显示自定义的文章类型A到Z索引，但它只是在三列中列出每个字母表下的第一篇文章，我认为循环有一些问题，但无法解决它

代码如下所示：

<div class="container">
    <div class="row">
        <div class="serviceproviders-inner-content haslayout">
<h2>A to Z Medication Guide </h2>
<?php

$query = new WP_Query(array(
                        \'post_status\'   => \'publish\',
                        \'post_type\'     => \'medicines\',
                        \'orderby\'       => \'title\',
                        \'order\'         => \'ASC\',
                        \'posts_per_page\'    => -1
                        ));

$post_count = $query->post_count;
$posts_per_column = ceil($post_count / 4);      

$rows = array();                                            
$count = 0;

while ($query->have_posts())

{ 
    $query->the_post(); 

    if($rows[$count] == "" ) { $rows[$count] = \'<div class="row">\'; }




        If ($letter != strtoupper(get_the_title()[0]))
        {
                // echo ($letter != \'\') ? \'</ul></div>\' : \'\';
                 $letter = strtoupper(get_the_title()[0]);  

        $rows[$count] = $rows[$count] .  \'<div class="col-sm-3">\' .  \'<h4>\'.strtoupper(get_the_title()[0]).\'</h4>\' .\'<div class="post-title">\'. \'<li><a href="\'.get_permalink().\'">\'.get_the_title().\'</a></li>\' . \'</div></div>\';  
        $count++;                           

        }   

        if ($count == $posts_per_column ) { $count = 0; } 


}
foreach ($rows as $row) { echo $row . \'</div>\'; }
?>
</div>
        </div>
    </div>