Plain text macros on new editor make a BE call that returns 404 and don't render on editor

Issue Summary

Environment

• New editor, plain text macros FF turned on

  Steps to Reproduce

1. Go to any Confluence space where the "The new editing experience gives you better looking pages, and new features like live macros." appears at the top.
2. Click the "Try it on a new page" link
3. Give the new page a title, then in the page body type "/sequence" and select the Sequence diagram macro.
4. At this point, note that in the browser console that there is already a 404 error trying to fetch the URL https://<instance>.atlassian.net/wiki/rest/api/content/:pageid/history/:historyid/macro/id/:macroid
5. Click the pencil icon to open the "Edit `Sequence diagram` macro" dialog
6. In the Content textarea on the right-hand side, enter the following text:  A->B: test
7. Click "Save" to close the dialog.
8. At this point, note that we have another similar 404 error;  AND the live preview does not show (just a big grey box where the macro should be).
9. Click "Publish" to publish the page.
10. When the page renders, the macro appears correctly (albeit with the grey artifact on the right hand side, as per CONFCLOUD-66806)

Expected Results

Macros should render normally on editor.

Actual Results

There is a 404 error in console and the live preview does not show (just a big grey box where the macro should be).

Workaround

Currently there is no known workaround for this behavior. A workaround will be added here when available