I agree that it has to be 12, but it's a very confusing image, at least to me, a non-scholar of Augusta National.
For one, it shows how it's not just the aesthetics of the hole that have changed -- it's the playing characteristics. Unless that guy at front right is a predecessor of Fred Couples, it appears that a ball used to be able to hang up on the front edge, even on the steeper side. And doesn't this photo show a lot more roll than this green has now?
To boot, the flag doesn't look like it says 12. More like 13 or even 15. Are we looking at its reverse side?