Could be a particularly hard problem instance for VF2; it manages to match 48 vertices out of 70 and then keeps on backtracking. When the algorithm gets stuck, it is trying to match vertices of degree 4 with each other.
I guess that the VF2 algorithm makes an erroneous assignment very early and then it takes a long time until it manages to backtrack there.
Could be a particularly hard problem instance for VF2; it manages to match 48 vertices out of 70 and then keeps on backtracking. When the algorithm gets stuck, it is trying to match vertices of degree 4 with each other.
I guess that the VF2 algorithm makes an erroneous assignment very early and then it takes a long time until it manages to backtrack there.