I know about that area. I've actually been using it alot recently as well, but with the same results.

At this point, I'm starting to think stoneshatter is broken. I've seriously spammed the spell for probably 6 or 7 hours non-stop over the last few days and have seen exactly zero improvements.

I've seen improvements in other spells that I'm using at the time (detect invis, etc), parry and weapon skills. I've had no such issues with any other spells thus far.

My affinity is 6, so I really can't imagine what the issue would be.