Theme editor styles (add_editor_style) not loaded in Site Editor “Styles” view and Template/Pattern preview iframes when Gutenberg plugin is active (WP 6.9.1 + GB 22.5.3)

Description

I’m using a hybrid theme with:

add_theme_support( 'editor-styles' )
add_editor_style( 'assets/css/editor.css' )

The editor styles apply correctly in the normal post/page block editor canvas.

However, when the Gutenberg plugin is active, my theme editor styles are not loaded in:

Site Editor → Styles (“Stile”) / visual identity view (Style Book-like screen)
Template / Pattern / Reusable block listing previews where each card uses a separate preview iframe

When I disable the Gutenberg plugin, the previews and the Styles screen iframes render correctly with the theme’s editor styles.

This looks like a regression or a missing integration in the Gutenberg plugin’s preview iframe/style pipeline for classic themes.

Step-by-step reproduction instructions

Activate a classic theme that declares editor styles:
add_theme_support( 'editor-styles' )
add_editor_style( 'assets/css/editor.css' ) (contains typography/button styles etc.)

Go to Site Editor and open:

Appearance → Editor → Styles (visual identity / typography preview)
Templates / Patterns / reusable blocks grid where cards show preview thumbnails

Observe the preview rendering.

Disable Gutenberg plugin and repeat steps 2–3.

Screenshots, screen recording, code snippet

Without Gutenberg Plugin:

With Gutenberg Plugin:

Environment info

WordPress: 6.9.1
Gutenberg plugin: 22.5.3
Theme type: Classic theme using add_theme_support( 'editor-styles' ) + add_editor_style()
Browser: Chrome

Please confirm that you have searched existing issues in the repo.

Yes

Please confirm that you have tested with all plugins deactivated except Gutenberg.

Yes

Please confirm which theme type you used for testing.

Block
Classic
Hybrid (e.g. classic with theme.json)
Not sure

Additional Screenshots

Site editor Styles with Gutenberg plugin active:

Site editor Styles with Gutenberg inactive:

may be related: #74081

Yes. Still relevant. Just updated the plugin to Version 22.8.2 and the issue persists.

Gutenberg plugin active:

Gutenberg plugin inactive, WP up to date:

@Mamaduka

Still relevant with plugin version 23.0.1. Still looks fine without plugin active. @Mamaduka could somebody please look into this? I'm worried this gets baked into core if nobody cares.

Could someone provide some theme data to reproduce this issue with a classic theme? Alternatively, can this issue be reproduced with a theme downloadable from the theme directory? At least, this issue cannot be reproduced with the default theme.

@t-hamano

@t-hamano Yes. As mentioned in the first line of the description I'm developing hybrid themes. As far as I observed, add_editor_style() simply does not apply the styles to the styles screen with Gutenberg active. No matter what. Even when I remove the theme.json from twentytwenty-four and enqueue my styles like above, they only apply without the plugin. The problem clearly has smth to do with the implementation of add_editor_style() in the plugin or how the theme support functionality works.

Thank you, I finally figured out how to reproduce the issue. It's very simple to reproduce the problem in a Gutenberg local environment.

Make the following changes.

diff --git a/test/emptytheme/style.css b/test/emptytheme/style.css
index 74cd7d858ad..f1f36885a9b 100644
--- a/test/emptytheme/style.css
+++ b/test/emptytheme/style.css
@@ -13,3 +13,7 @@ Text Domain: emptytheme
 Emptytheme WordPress Theme, (C) 2021 WordPress.org
 Emptytheme is distributed under the terms of the GNU GPL.
 */
+
+p {
+       background-color: red !important;
+}

Activate Emptytheme. This theme already has the following code.
```
add_editor_style( 'style.css' );
```
Create a pattern that includes paragraph blocks.
Access the Patterns page.

WordPress 6.9	WordPress 7.0 RC2 or Gutenberg plugin enabled

In other words, this is a regression that will occur in WordPress 7.0. Let's identify and fix the problem.

@t-hamano

@t-hamano Thank you for verifying. 🙂

@Azragh

@Azragh, Regarding the pattern preview issue, it should be fixed in #77957. However, the issue in the style book cannot be reproduced yet. Do you know a reliable way to reproduce it?

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Theme editor styles (add_editor_style) not loaded in Site Editor “Styles” view and Template/Pattern preview iframes when Gutenberg plugin is active (WP 6.9.1 + GB 22.5.3) #75779

Description

Step-by-step reproduction instructions

Screenshots, screen recording, code snippet

Environment info

Please confirm that you have searched existing issues in the repo.

Please confirm that you have tested with all plugins deactivated except Gutenberg.

Please confirm which theme type you used for testing.

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Theme editor styles (add_editor_style) not loaded in Site Editor “Styles” view and Template/Pattern preview iframes when Gutenberg plugin is active (WP 6.9.1 + GB 22.5.3) #75779

Description

Description

Step-by-step reproduction instructions

Screenshots, screen recording, code snippet

Environment info

Please confirm that you have searched existing issues in the repo.

Please confirm that you have tested with all plugins deactivated except Gutenberg.

Please confirm which theme type you used for testing.

Activity

Azragh commented on Feb 20, 2026

Azragh commented on Feb 20, 2026

github-actions commented on Mar 29, 2026

Azragh commented on Mar 31, 2026

github-actions commented on May 1, 2026

Azragh commented on May 1, 2026

t-hamano commented on May 4, 2026

3 remaining items

Azragh commented on May 5, 2026

t-hamano commented on May 5, 2026

Azragh commented on May 5, 2026

t-hamano commented on May 5, 2026

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