Finally figured this out.
Somewhere in the beginning of the page, I was doing this to get the current blog’s name:
<?php $current_site = get_blog_details(); echo $current_site->blogname; ?>
That has always worked until I upgraded WP and ACF recently. Then all of the sudden, the issue of media not loading and blowing up the memory started happening.
I finally found that removing this one line fixed the whole page so I rewrote it to this and now everything works:
<?php global $blog_id; $current_blog_details = get_blog_details( array( 'blog_id' => $blog_id ) ); echo $current_blog_details->blogname; ?>
