App sometimes doesn't return properly from lock

If we lock our app, and then restart it a few seconds later, the screen doesn’t update. Ever. It seems the app is running and receiving updates and you can hear sounds, but the display never changes. This happens mostly on iPad mini and iPhone5 and mostly with iOS 6.0.2. It rarely, if ever, happens on iPad 2. We are able to get the same freeze up happening on the cocos2d-x hello world app also, so it seems it’s not related to the specifics of our app.
Has anyone else seen this?

It is the first time i heard this issue.
I will try to run samples on iPad mini to checkout it.

I believe this is really time dependent. It seems to occur if you wait about 2-3 seconds after pressing the power button before unlocking it again on the
iPad Mini running 6.0.2 and iPhone 5 running 6.0.1. I have not been able to get it to happen on normal iPads or devices running ios 5.x

When debugging it, the update and draw calls are still being made, but what is drawn seems frozen on the screen. It displays what was displaying on
the app before pressing the lock button. I was able to replicate this on TestCpp and HelloWorld after a few tries. It seems like it might happen more often
when there is more occurring in the draw code.