Description

When a “Table of Contents” block is present in the post and changes are made to a heading block, the Save button remains disabled, even though changes have been made. However, making changes to any other block (other than the heading block) correctly enables the Save button.

This issue prevents users from saving their changes after modifying headings unless they interact with another block, which disrupts the workflow.

Step-by-step reproduction instructions

1. Create a new post or edit an existing one in the Gutenberg editor.
2. Add a “Table of Contents” block to the post.
3. Add a Heading blocks to the content.
4. Make a change to the Heading blocks (e.g., change the text).
5. Observe that the Save button remains disabled.
6. Make a change to any other block (e.g., a Paragraph block).
7. Observe that the Save button is now enabled.

Screenshots, screen recording, code snippet

• WordPress: 6.8-alpha-59467
• PHP: 8.2.26
• Server: Apache/2.4.62 (Debian)
• Database: mysqli (Server: 11.4.4-MariaDB-ubu2404 / Client: mysqlnd 8.2.26)
• Browser: Chrome 131.0.0.0
• OS: macOS
• Theme: Twenty Twenty-Five 1.0
• MU Plugins: None activated
• Plugins: Gutenberg 19.8.0-rc.1

Environment info

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