I ended up with very good luck last night at about 8pm Eastern. My trick: don't wait.
Click to personalize. It redraws the screen and either says something like "working... click back in a minute" or it only says "click back in a minute". If it doesn't say working, it's not going to personalize, so you might as well click immediately to get back to the screen where you can click personalize again. If it does say working, you can let it sit a bit to let it work.
Point is that if it doesn't say the word "working", you're wasting your time waiting; the Paizo site is not doing anything at all for you at that time.