3 $item should be $post everywhere
source | link

Use the old method of adding the relationship field -> Post Object

<?php while (have_posts()) : the_post(); ?>
<div class="entry-content"> 
    <h1 class="content-headline">Package: <?php the_title(); ?></h1>
</div>
<div class="package-description" style="padding:15px 10px;background:white;">
    <?php the_content(); ?>
</div>
<?php 

$posts = get_field('package_items');

if( $posts ): ?>

<ul>    

<?php foreach( $posts as $post): // variable must be called $post (IMPORTANT) 

    setup_postdata($post); ?>

        <li>
            <a href="<?php echo get_permalink( $item$post->ID ); ?>">
                <?php echo get_the_title( $item$post->ID ); ?>
            </a>
        </li>

<?php endforeach; ?>

</ul>

<?php wp_reset_postdata(); // IMPORTANT - reset the $post object so the rest of the page works correctly

endif; endwhile; ?>

Use the old method of adding the relationship field -> Post Object

<?php while (have_posts()) : the_post(); ?>
<div class="entry-content"> 
    <h1 class="content-headline">Package: <?php the_title(); ?></h1>
</div>
<div class="package-description" style="padding:15px 10px;background:white;">
    <?php the_content(); ?>
</div>
<?php 

$posts = get_field('package_items');

if( $posts ): ?>

<ul>    

<?php foreach( $posts as $post): // variable must be called $post (IMPORTANT) 

    setup_postdata($post); ?>

        <li>
            <a href="<?php echo get_permalink( $item->ID ); ?>">
                <?php echo get_the_title( $item->ID ); ?>
            </a>
        </li>

<?php endforeach; ?>

</ul>

<?php wp_reset_postdata(); // IMPORTANT - reset the $post object so the rest of the page works correctly

endif; endwhile; ?>

Use the old method of adding the relationship field -> Post Object

<?php while (have_posts()) : the_post(); ?>
<div class="entry-content"> 
    <h1 class="content-headline">Package: <?php the_title(); ?></h1>
</div>
<div class="package-description" style="padding:15px 10px;background:white;">
    <?php the_content(); ?>
</div>
<?php 

$posts = get_field('package_items');

if( $posts ): ?>

<ul>    

<?php foreach( $posts as $post): // variable must be called $post (IMPORTANT) 

    setup_postdata($post); ?>

        <li>
            <a href="<?php echo get_permalink( $post->ID ); ?>">
                <?php echo get_the_title( $post->ID ); ?>
            </a>
        </li>

<?php endforeach; ?>

</ul>

<?php wp_reset_postdata(); // IMPORTANT - reset the $post object so the rest of the page works correctly

endif; endwhile; ?>
2 This is working for me now ...
source | link

You already have setup the post data, you don't need to mentionUse the ID ... moreover you can call any custom fields withinold method of adding the relationship post in the loop..field -> Post Object

<?php while (have_posts()) : the_post(); ?>
<div class="entry-content"> 
    <h1 class="content-headline">Package: <?php the_title(); ?></h1>
</div>
<div class="package-description" style="padding:15px 10px;background:white;">
    <?php the_content(); ?>
</div>
    <?php 
        $items
$posts = get_field('package_items');
        ?>
        <?php if( $items$posts ): ?>
            <ul>
        <ul>     

<?php foreach( $items$posts as $item $post): ?>
  // variable must be called $post (IMPORTANT)  

   <?php setup_postdata($item$post); ?>
         
        <li>
                    <a href="<?php the_permalinkecho get_permalink( $item->ID ); ?>">
                        <?php the_titleecho get_the_title( $item->ID ); ?>
                    </a>
                </li>
             
<?php endforeach; ?>
             
</ul>
        <?php endif; ?>
         <?php wp_reset_postdata(); // IMPORTANT - reset the $post object so the rest of the page works correctly ?>
<?php
endif; endwhile; ?>

You already have setup the post data, you don't need to mention the ID ... moreover you can call any custom fields within the relationship post in the loop..

<?php while (have_posts()) : the_post(); ?>
<div class="entry-content"> 
    <h1 class="content-headline">Package: <?php the_title(); ?></h1>
</div>
<div class="package-description" style="padding:15px 10px;background:white;">
    <?php the_content(); ?>
</div>
    <?php 
        $items = get_field('package_items');
        ?>
        <?php if( $items ): ?>
            <ul>
            <?php foreach( $items as $item ): ?>
            <?php setup_postdata($item); ?>
                <li>
                    <a href="<?php the_permalink(); ?>">
                        <?php the_title(); ?>
                    </a>
                </li>
            <?php endforeach; ?>
            </ul>
        <?php endif; ?>
         <?php wp_reset_postdata(); // IMPORTANT - reset the $post object so the rest of the page works correctly ?>
<?php endwhile; ?>

Use the old method of adding the relationship field -> Post Object

<?php while (have_posts()) : the_post(); ?>
<div class="entry-content"> 
    <h1 class="content-headline">Package: <?php the_title(); ?></h1>
</div>
<div class="package-description" style="padding:15px 10px;background:white;">
    <?php the_content(); ?>
</div>
<?php 

$posts = get_field('package_items');

if( $posts ): ?>

<ul>     

<?php foreach( $posts as $post): // variable must be called $post (IMPORTANT)  

    setup_postdata($post); ?>
 
        <li>
            <a href="<?php echo get_permalink( $item->ID ); ?>">
                <?php echo get_the_title( $item->ID ); ?>
            </a>
        </li>
 
<?php endforeach; ?>
 
</ul>

<?php wp_reset_postdata(); // IMPORTANT - reset the $post object so the rest of the page works correctly

endif; endwhile; ?>
1
source | link

You already have setup the post data, you don't need to mention the ID ... moreover you can call any custom fields within the relationship post in the loop..

<?php while (have_posts()) : the_post(); ?>
<div class="entry-content"> 
    <h1 class="content-headline">Package: <?php the_title(); ?></h1>
</div>
<div class="package-description" style="padding:15px 10px;background:white;">
    <?php the_content(); ?>
</div>
    <?php 
        $items = get_field('package_items');
        ?>
        <?php if( $items ): ?>
            <ul>
            <?php foreach( $items as $item ): ?>
            <?php setup_postdata($item); ?>
                <li>
                    <a href="<?php the_permalink(); ?>">
                        <?php the_title(); ?>
                    </a>
                </li>
            <?php endforeach; ?>
            </ul>
        <?php endif; ?>
         <?php wp_reset_postdata(); // IMPORTANT - reset the $post object so the rest of the page works correctly ?>
<?php endwhile; ?>