Hi Simon,

I guess you posted more code, but it got stripped out by the comment text escaping. It should work if you modify the code like this:

$blocks = parse_blocks( get_the_content() );
foreach ( $blocks as $block ) {
	if ( 'acf/page-header-image' === $block['blockName'] ) {
		echo render_block( $block );
		break;
	}
}

Hope that helps!

Best,
Florian