Figured it out, had to delete the copy of the world that had experimental option checked on it, and deleted all other worlds to be safe, all achievements work now.
Ezekiel, by "requested information" do you mean affected version? If so, this was provided 28/Nov/13 soon after your request.
This issue still exists in version 1.8.4 (the "steps to reproduce" generate an invisible static block).
Figured it out, had to delete the copy of the world that had experimental option checked on it, and deleted all other worlds to be safe, all achievements work now.