Get the selected posts IDs to use in bulk edit AJAX call

After searching through WordPress core I found the following on lines 1051 – 1057 of wp-admin/includes/class-wp-posts-list-table.php

if ( post_type_supports( $screen->post_type, 'title' ) ) :
    if ( $bulk ) : ?>
        <div id="bulk-title-div">
            <div id="bulk-titles"></div>
        </div>

<?php else : // $bulk ?>

So, in order for the #bulk-titles element to be part of your admin list the post type your working with needs to support title.

New custom posts types do support title by default. My custom post types are not using titles so I had set supports => false as an argument passed to register_post_type call.

Not supplying the supports argument or setting it to an array that includes title as a member solved the bulk edit problem, and I hid the title on post edit page using CSS.