Apparently the solution does not for everyone. However you still have a newer driver than the one I recomended so maybe that is the problem. I used this one: http://www.geforce.co.uk/drivers/results/111170
Anyway It worked for me and maybe it will for someone else aswell. I can also say that Ansel still crashes in my case if I launch the game as Standalone from Editor. However if I package the game and then launch the exe the Ansel works just fine and I had exactly the same problem as you. Before the rollback the Ansel appeared when pressing Alt+F2 but it crashed when snaping anything other than regular screenshot or HDR. The driver rollback helped me.