Not sure if it is the source of your problem, but it looks to me as if there isn't enough overlap between the images. There is a lot of distortion in the edges, it might be a factor. I would reccomend flying at a higher altitude, or maybe choosing better optics with less distortion. I am no expert, but this is my two cents on the matter.
(tried the set, same results as you, only 2 images aligned w/129 points)