the_content() doesn’t make ‘Read more’ link for the last post

I used this custom code for my child theme.

<div class=”post_description clearfix”>

<?php if(boc_blog_full_post_content()){
the_content();
}else {
the_excerpt();
}
?>

<ul class=”post-tag”>
<?php if(get_the_tags()) { ?>
<?php the_tags(”,’, ‘); ?>
<?php } ?>

</div>

It is supposed to generate the title, content abbreviation, and “Read more” links, but the linke of ‘Read more’ in the final article is lost.
https://ibb.co/tbGVLzc
https://ibb.co/SwbSbGQ

The last article’s code:
https://ibb.co/MV40LPF