Two iPhones - one syncs reminders, the other doesn't
I have two iPhones - one is a work-issued phone (an iPhone 5), and the other (a 5S) is my personal phone. I've also got an iPad Air. All of them have the most current iOS (8.1.3). For some reason, the Reminders app on my 5S won't sync with the other devices.
If I create a reminder on my 5, or on my iPad, or on iCloud, it will instantly update on all of those devices. But not on the 5S. If I create a reminder on my 5S, it seems to upload to the others (and, actually, I did it just now and all of a sudden it synced everything else from the other devices).
Any ideas why my 5S won't pull down updates on Reminders?
iPhone 5s, iOS 8.1, null