Updating to WP 6.4 breaks fse-hybrid-theme placeholder blocks

[lukeoly-akqa]

Updating to WP 6.4 brakes placeholder blocks using WP core functions like have_posts() and the_post(); in blocks like singlepost.php
This results in all template data inside the while loop not being output on the page.

header.php works on the homepage and sample page but not on posts. Template data of header.php is completely ommitted on posts.

[lukeoly-akqa]

After some more digging is seems that this is being caused by changes to the WordPress Loop in block themes in 6.4
https://make.wordpress.org/core/2023/11/13/main-query-loop-handling-for-block-themes-in-6-4/