Oh no....I had this one when I went to 7.1.2.
The recommended action you'll find all over the web is to go into settings, log out of icloud, log back in. Some recommend rebooting after you've logged out, but before you sign back in.
It never worked for me, but it has for others. And near as I can tell, it's not a JB issue, as most reports were on stock devices. I ended up restoring twice; once from backup--the problem was back a couple of days later--and finally as new, no backup. That was what finally solved it for me.