iOS app notifications have not been working for about 27 hours (since yesterday around noon eastern time).
The problem is an internal certification used to verify identities expired. In order to fix it, I had to renew my developer status with Apple. I had let this lapse in March (see ios app expiring
topic). So, it's likely the iOS app will be back in the Apple App store again (soon if not already).
The process of doing certifications is kind of complicated and my first attempts to fix it don't seem to have worked. I'll keep working on it. Also, there may be an alternate way to do notifications with a cert that doesn't expire. So, I'm currently looking into that too.
I suspect it may be another day or two before iOS app notification work again.
[ update: fixed now ]