Sharepoint site page header web part has lost editing capability, now cannot edit background image.

In the process of building a sharepoint page based on the newsletter template and we replaced the default header background image several days ago.

Now when logged in cannot access the image edit overlay menu at all. This disappeared yesterday after reopening the page.

Screencapture inserted below for visual reference.

As can be seen on the standard page when it has been created the header element accesses a menu overlay with which to update or replace the background image asset. Screencapture inserted below for visual reference of this.

The question here is (a) what has happened to the page leading to the loss of editing functionality and (b) what can be done to restore this editing functionality. There is no way to copy web parts between two pages so we cannot simply create a new page and copy all other 44 web parts over to this new page.