Dear Ina,
Actually my processing area is not those areas, check this:
Also I tried to process only 3 lines with 7 image in each of theme, again same results. I think its a DSM generation problem, because when I use a perfect external point cloud, again these problems occurs. Check out this post
https://community.pix4d.com/t/6374-Rounded-edges-near-roof-even-when-I-use-external-perfect-point-cloud