I don't want to hijack, but wanted to let you know I'm watching this thread like a hawk because I have exactly the same problem
. Don't let it die!
I've been following the advice from the Squat Rx video
that deals with GM'ing out of the hole and doing Goblet Squats and Good Morning Squats as assistance exercises. I also found Kelly Starrett's midline stabilization series on the CrossFit Journal to be extremely helpful. I'm also thinking that more air squats nose-to-wall might help. I haven't solved the issue, but I think it is getting better.
Since I started with SS, I've never even really given HBBS a fair shake, and now I'm thinking maybe I should. My front squat is also terrible, but since I have to use such a lighter weight for that, I always feel like I'm not getting a good CNS hit for strength development.
Stacey, please share any insights or breakthroughs you gain about this, I'd love to hear them.