I have fields and tabs published for display on the registration form. The registration form worked just fine in CB 1.1. I have also unpublished the tabs for all third party CB modules.

And as I said before, my Check Users Database comes out green.

Should I try uninstalling CB 1.2 and reinstalling?

I found the cause...I had in table CB Plugin Manager the CB Core set for Registered .

Yay! Thanks for figuring this out! Apparently this was my problem too. It must be a setting that's somehow set by upgrading from 1.1 to 1.2 because I definitely didn't set it to that manually.

THank you so much for posting what you did to fix it... I had the same issue and its because I had my CBcore set to registered! Thanks!