Has anyone else noticed an apparent oddity in ATK puzzle M43441? The cell r8c5 looks as though it had been pasted there, literally, with scissors and glue. That cell is a bit discolored compared to the rest of the grid, and its borders are less distinct than on other cells.
Additionally, this cell destroys the usual 180-degree rotational symmetry found in most ATK (and other) patterns.
Could it be that the original puzzle was defective (perhaps it had multiple solutions), and that adding this cell (and updating a couple of the sums to match) fixed the problem??