Sander,
in my examples, using the downsample option (I think something like -d 2) usually helped. Also, BlindSolver seems to be better at solving unprocesssed images that processed images. In some processed images, it helps to make them more dim (e.g. with moving the midtones slider in Histogram transform to the right). I also had a few images that I was not able to solve, such as Vicent's M51 (which is heavily processed), but I dont know if the web version would have solved these.
Georg