There is a chance that you had the same issue I did i.e. trying to edit the place of the extra action button while you have some ability on it. The edit mode doesnt seem to allow for that.
Instead, when you dont have the button appear because there is no extra ability in this area, then go into edit mode and tick on the “extra abilities” so that the grid area that you can drag shows up. That way you could select and drag it where you want it to be as usual.