Categories block: content can differ between editor and front-end

[chthonic-ds]

Description

A Categories block can be configured to unintentionally display different content for the editor view and front-end view.

Step-by-step reproduction instructions

The reproduction steps here use the following set-up:

• Parent category: Collection
• Child categories of Collection: Bat, Cat, Hat

Collection should not be assigned to a post, while each child category should be assigned to at least one post each.

1. Create a new post and add a Categories block. The Categories settings panel should show all settings as inactive.
2. Publish the post and observe the empty parent category is displayed in the editor view and omitted from the front-end view.
3. Add another Categories block and enable settings: Show post counts and Show hierarchy.
4. Update the post and observe the parent category displays a count of 0 in the editor view and the sum of the child counts in the front-end view.

Screenshots, screen recording, code snippet

Category structure

Editor view

Front-end view

Environment info

WP 5.9 beta2, Gutenberg active or inactive, Twenty Twenty-Two
Chrome 96.0.4664.45
Windows 10

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

[t-hamano]

Thank you for submitting the issue and I apologize for the delay in replying.

I was able to reproduce it with the latest gutenberg. When the output was compared to the category block of the classic widget, it matched the output of the front end, so it must be the editor's output that is wrong. I would like to investigate the code on the editor side.

Test Result

Add child categories:

Tie categories to posts:

The editor view:

The front-end view

[t-hamano]

Upon further investigation, I found that the number of front-end cases in the first place may not be correct for some conditions.
Below is the ticket I submitted to the core:
https://core.trac.wordpress.org/ticket/56892