Steps to reproduce

1. Starting at URL: https://wordpress.com/block-editor/post/
2. Switch to the Code Editor
3. Put the following in the post body:

First paragraph
<!--more-->
Second paragraph

4. Save a draft
5. Return to the posts list and edit the draft
6. In the dialog, click the button to Convert To Blocks.

What I expected

The blocks should appear in the correct order, with the Read More break in between the two paragraphs.

What happened instead

The blocks are in the wrong order: First paragraph, Second paragraph, Read More.

Browser / OS version

Firefox 76.0 on macos 10.15e4

Context / Source