What problem does this address?

This is a UX improvement suggestion. Here is a walkthrough of what I experienced, simulating a new user.

When I click any block where I wish to add an editor note, and subsequently click the Note button on the top-right menu, I see a blank right side bar with the message - No notes available - Only logged in users can see notes

It takes me a few more moments to understand how to add a new note, by clicking the block ellipsis menu.

What is your proposed solution?

If a user has a block selected, and clicks the Notes menu, it would be nice if they see an Add note button in the right side bar ( if there are existing notes, there could be an Add new note button that shows up below ).

For most blocks we are used to seeing important options for the block on the right side bar. Since we have a dedicated sidebar menu for notes, it may be helpful to include these buttons, for easy access to the feature.

The button should only show up if a specific block is selected, else the behavior should be similar to what we currently have - show all notes on that page/ post without highlight.