Meta boxes hooked on 'edit_form_after_title' don't appear on block-editor page

[apedog]

The Gutenberg/block-editor page does not print meta boxes hooked on edit_form_advanced action. Meta boxes hooked on edit_form_advanced only show up in classic editor mode.

Block-Editor pages should still print out the meta boxes. Even if they cannot, for technical reason, be printed directly after the title.

I believe this should be viewed as a regression/bug. Not a feature request/enhancement.

[apedog]

That's an unfortunate copy-paste typo.
Hook I'm talking about is edit_form_after_title

I've no idea how edit_form_advanced meta boxes behave on block editor pages.

[poena]

Hi
This issue was discussed during a triage session today and it was decided to move it to the 5.8 milestone to get more eyes on it.

When looking for background information about if or why there is no fallback for printing the metaboxes elsewhere, we found this migration guide: ​https://github.com/danielbachhuber/gutenberg-migration-guide.

[hellofromTonya]

Today is a freeze for 5.8 as it's Beta 1 day. As investigation is ongoing and there's not a patch yet, punting to 5.9 for resolution.

[costdev]

Can someone clarity this issue for me?

The following in functions.php shows a metabox at the bottom of the Gutenberg block editor when adding a new post and editing an existing post.

<?php

function add_metabox_using_edit_form_after_title( $post ) {
        add_meta_box(
                'a-meta-box',
                'A Meta Box',
                'render_a_meta_box',
        );
}

function render_a_meta_box( $post ) {
        ?>
        <h1>Hello World!</h1>
        <?php
}

add_action( 'edit_form_after_title', 'add_metabox_using_edit_form_after_title', 10, 1 );

[costdev]

Metabox being printed when hooking edit_form_after_title

[hellofromTonya]

With 5.9 Beta 1 release happening in a few hours and ongoing discussion and no patch yet, moving this ticket to 6.0.