Description

User story: As a user, I expect to be able to select a classic menu within an existing navigation block.

The "Classic Menus" section does not appear in an existing Navigation's block "Select Menu". Rather, it only appears in adding a new nav block.

Why is this a problem?

How will a user know that they must first delete an existing nav block and then insert a new one in order to select one of their existing (classic) menu?

Think of the user who is first upgrading to WordPress 5.9, has existing menus, and then activates a block theme such as Twenty Twenty-Two (TT2). With say TT2, the header menu by default upon activation is a page listing. So the user does these steps:

• Step 1: Clicks on "Customize" button on the TT2 theme or Appearance > Editor (beta) menu item. Site Editor opens.
• Step 2: Clicks on the header navigation block either directly or via list view.
• Step 3: Clicks on "Select Menu". Notice the existing classic menu(s) are not there.

👉 How does the user know what to do next?

The next steps are:

• Step 4: Delete the existing header nav block (OR click on "Create new menu" which inserts a new nav block).
• Step 5: Insert a new nav block into the header.
• Step 6: Click on "Select Menu". Now the classic menus are there and selectable.

What happens if they select the wrong one?
Repeat steps 4-6.

The expected behavior is: Steps 1-3 and then classic menus are shown and selectable.

Step-by-step reproduction instructions

1. Activate a non-block theme. Let's use Twenty Twenty-One (TT1).
2. Add a "Main Menu" by going to Appearance > Menus and creating a new menu called "Main Menu" and set it as primary menu.
3. Activate the Twenty Twenty-Two (TT2) or any other block theme.
4. Open the Site Editor by clicking on "Customize" on the theme or clicking Appearance > Editor (beta).
5. Click on the navigation block in the header or open list view and then select the block.
6. Click on "Select Menu".

Screenshots, screen recording, code snippet

Environment info

• WordPress: 5.9 RC3
• OS: macOS Big Sur
• Browsers: Chrome, Edge, Firefox, Safari
• Plugins: none
• Theme: TT1 and then TT2

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