Try this, just before the_title, try to echo the $post->ID. At least then you will know if you are getting the correct post or if there is a disconnect between the two.
You can also try this:
$ID = $post->ID;
echo get_the_title( $ID );
You can also try this, this is code from my page where i use
$posts = get_sub_field('carousel_project'); // relationship field
if( $posts ): ?>
<?php foreach( $posts as $post): // variable must be called $post (IMPORTANT) ?>
<?php setup_postdata($post); ?>
<?php if( have_rows( 'repeater_multimedia' ) ): ?> // repeater field inside of the related post
<?php while( have_rows( 'repeater_multimedia' ) ): the_row(); ?>
Maybe if you change your top part to this, you might have better luck.
