ACF breaks the block editor if blocks are rendered inside of an ACF block

Hey,

I just wanted to let you know that the block editor hangs as soon as you render block content within an ACF block. I suspect this only occurs when inner blocks are present.

I know this bug has been fixed in the past: https://github.com/AdvancedCustomFields/acf/issues/682. But now it doesn't seem to be working anymore.

This error only occurs if the block content has not yet been cached by ACF. That's why I haven't noticed it for a long time.

I think you should know that.

I have now fixed this bug for myself by doing some operations in my ACF blocks render callback function, but I think this bug should also be fixed directly at ACF:

In my callback function:

function my_acf_block_render_callback( $block, $content, $is_preview, $post_id, $wp_block, $context ) {

    //...
    
    /*
    * HOTFIX: ACF breaks the editor if block content is rendered via do_blocks();
    */

    if( $is_preview && doing_filter('render_block_content_in_editor_filter') ) {
        $block_content = acf_render_blocks_in_editor( $block_content, $content, $wp_block, $block );
        echo $block_content;
        return;
    }
    
    //...
    
}

To convert <InnerBlocks> tags to content:

function acf_render_blocks_in_editor( $html, $content, $wp_block, $block ) {

    $content = str_replace( '$', '\$', $content );

    // Wrap content in our acf-inner-container wrapper if necessary.
    if( $wp_block && apply_filters( 'acf/blocks/wrap_frontend_innerblocks', true, $block['name'] ) ) {

        // Check for a class (or className) provided in the template to become the InnerBlocks wrapper class.
        $matches = array();

        $class = 'acf-innerblocks-container';
        if( preg_match( '/<InnerBlocks(?:[^<]+?)(?:class|className)=(?:["\']\W+\s*(?:\w+)\()?["\']([^\'"]+)[\'"]/', $html, $matches ) ) {
            $class = isset( $matches[1] ) ? $matches[1] : 'acf-innerblocks-container';
        }

        $content = '<div class="' . $class . '">' . $content . '</div>';
    }

    return preg_replace( '/<InnerBlocks([\S\s]*?)\/>/', $content, $html );

}

To output rendered block content in the editor:

function get_block_content( $post_id ) {

    $post = get_post( $post_id );
    $content = isset( $post->post_content ) ? $post->post_content : '';

    return do_blocks( $content );

}

add_filter( 'render_block_content_in_editor_filter', 'get_block_content' );

Start by reproducing the hang with an ACF block containing InnerBlocks and uncached content. Read the render callback and the named acf_render_blocks_in_editor(), get_block_content(), and render_block_content_in_editor_filter paths in the issue. Done means the block editor no longer hangs when nested block content is rendered before ACF caches it.