Description

When using the Navigation block and added sub-menu items, I noticed that there appears to be a regression in behavior where I'm unable to see the sub-menu item upon addition and, if I remove it, it also removes the parent menu item.

Step-by-step reproduction instructions

1. Add a navigation block.
2. Add a few menu items.
3. Add a sub menu item.
4. See initial state where you can't seem to add in a link to the sub menu container.
5. Try to delete the sub menu item and notice it deletes the parent.

Screenshots, screen recording, code snippet

Environment info

• WordPress 5.9-alpha-52262
• Gutenberg 12.01
• TT1 blocks
• 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