Added security, lost masonry layout

We just (1) changed to SSL and (2) added security 'Defender' by WPMU DEV and have since lost the masonry layout in the blog index page.

I added this to my wp-config as per: https://docs.generatepress.com/article/disallow-php-execution ...

add_action( 'after_setup_theme', 'tu_remove_hooks_php_check' );
function tu_remove_hooks_php_check() {
remove_action( 'admin_notices','generate_hooks_php_check' );
}

But the blog still looks odd, layout here: https://thecubelab.co.uk/blog/

Not sure if the security plugin caused this as it was working before but we have made more changes since I last looked but can't think what else it can be.

Any ideas why that might be?

Thanks!