Description

This is a little difficult to explain, but follow these steps.

First, delete all blocks from the Single Posts template, insert just a Content block, and enable the "Inner blocks use content width" setting.

The template HTML should be like this:

<!-- wp:post-content {"layout":{"type":"constrained"}} /-->

Create a new post, insert a Heading block and save the post. The Heding block has the align control:

Back to the Single Posts template, select the Content block, enter a number in the "Content Width" or "Wide Width" field, then delete them, and save the template.

The template HTML should be like this. Note that the values are added as an empty string.

<!-- wp:post-content {"layout":{"type":"constrained","contentSize":"","wideSize":""}} /-->

Back to the post. The Heading block DON'T have the align control:

If contentSize or wideSize is empty, I think the attribute itself shouldn't be saved.

Step-by-step reproduction instructions

Described above.

Screenshots, screen recording, code snippet

Environment info

No response

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