number of postviews not change in Main page

hi , i have strange problem
i use these codes to show number of post views

in function.php :

<?php
function getPostViews($postID){
    $count_key = 'post_views_count';
    $count = get_post_meta($postID, $count_key, true);
    if($count==''){
        delete_post_meta($postID, $count_key);
        add_post_meta($postID, $count_key, '0');
        return "???? ??????";
    }
    return $count.' ??????';
}

// function to count views.
function setPostViews($postID) {
    $count_key = 'post_views_count';
    $count = get_post_meta($postID, $count_key, true);
    if($count==''){
        $count = 0;
        delete_post_meta($postID, $count_key);
        add_post_meta($postID, $count_key, '0');
    }else{
        $count++;
        update_post_meta($postID, $count_key, $count);
    }
}
?>

and in single.php :

<?php setPostViews(get_the_ID()); ?><?php echo getPostViews(get_the_ID()); ?>

and in my index.php :
<?php echo getPostViews(get_the_ID()); ?>

the problem is the views counter change and increase when i go to post ( read more …) but when i came back to my home page the counter roll back to previews number and nothing changed !!!

whats the problem ?!?

and another strong thing is when i login as admin the real number of post views showed !! and everything works fine .

it seems the problem is with Guest users or something like that
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