wiki change note lost between review rounds

On dev site editing a wiki page (I used an existing one) you can press 'preview' to see the changes without committing it to history.
There is also a 'change note' line to edit with a comment which should go into the history.

When I enter a 'change note' and press 'preview' I expect the change note to be filled again when the page reloads.
Instead the change note field is empty.