I can see the arrow and the scale but only if the whole image is shown on the screen.
If I zoom in, the scale and arrow don’t appear on the zoomed image, even if I uncheck then recheck the Mapping tools layer or remove it and dot it again.
This means that the scale is not linked to the display which makes it of no use. Indeed what we expect from a scale indicator is to indicate at what scale the displayed image is at the current zoom level.
More precisely, the scale does change with the zoom level but both the scale indicator and the north arrow are out of view because they remain at the same place.
What would be nice is to have a simple textbox at the bottom of the screen indicating the scale e.g. 1/50,000 as is the case with QGIS. It may even allow to select/type the desired display scale.