TinyMCE's "Clear Formatting" button doesn't remove lists and headings

Question

Pressing the "Clear Formatting" toolbar button removes styles like bold and italics just fine, but it leaves lists and headings (h1, h2, etc.) as-is. Is there a way to include all elements when clearing the formatting of the content? I've searched and searched but can't seem to find any results pertaining to what I want to do.

I'm mostly using an Advanced Custom Fields WYSIWYG field, but I've tried with WordPress' default Classic Editor as well. I found a single post that showed using the removeformat_selector attribute in TinyMCE's initialization, but that doesn't work. This is what I tried: (using ACF's approach to TinyMCE's init customization)

add_action( 'acf/input/admin_footer', function() {
    ?>
    <script type="text/javascript">
        ( function( $ ) {
            acf.add_filter( 'wysiwyg_tinymce_settings', function( mceInit, id, field ) {
                mceInit['removeformat_selector'] = 'ul,li,b,strong,em,i,span,h1,h2,h3,h4,h5,h6,blockquote,pre,code';
                return mceInit;
            } );
        } )( jQuery );
    </script>
    <?php
} );

Answer 1

I need to answer my own question here. I was using the attributes from TinyMCE v3, but it needed to use the v4 format. Here's what works:

add_action( 'acf/input/admin_footer', function() {
    ?>
    <script type="text/javascript">
        ( function( $ ) {
            acf.add_filter( 'wysiwyg_tinymce_settings', function( mceInit, id, field ) {
                mceInit['formats']['removeformat'] = [{ selector: 'h1,h2,h3,h4,h5,h6,ul,li,b,strong,em,i,span,blockquote,pre,code', remove: 'all', split : true, expand : false, block_expand: true, deep : true }];
                return mceInit;
            } );
        } )( jQuery );
    </script>
    <?php
} );