We do increase the sharpness a bit which should help with the image stitching. I don't suspect that the sharpness is the cause of the artifacts since this is also what everyone else is flying with. Could it be a red herring?
Please check the EXIF data of each photo to see if shutter speed or ISO is changing at all. If it isn't then for some reason your exposure mode wasn't set to auto by the app. If it is changing, then the DD auto is working.