In "Medum" Petrie reported that the now dilapidated brickwork of M17 near the Meydum Pyramid had no three-dimensional features like recessed panels and false doors on either side including the east side, where two other mastabas nearby, M16 and M6, do have a paneled feature creating the iconic palace facade. In "Medum", Petrie described how the brick walls were built up from below the ground level using indicator marks at the four corners. The four corners were braced by four vertical retainer walls in the shape of an " ┐" . Here are photos I took in September 2018 at the northeast corner when I visited. You can still see the tops of the vertical retainer walls. You can also see a flat pavement made from bricks. But then you see what appears to be the remnants of the base of the original mastaba wall. This does not look like a straight base to me. It looks indeed niched. What needs to be done is to clear the debris of the entire east face of M17 and look at this baseline, if that is what it is, to see if it is indeed paneled.