I randomly stumbled upon this when I was testing sleep mode behavior when a game is currently running. At first I thought my device was completely frozen, and I had to use the reset button to get it out of this state. I then realized that it only happens when I hold A or B (or both) before pressing the sleep button. When I do this, the device gets stuck on the lock screen and is completely unresponsive to the sleep button. However, if I press whichever button was originally pressed (A or B), the device will suddenly allow me to unlock it again. This issue happens any time you go into sleep mode, not just when you are running an app.
This is maybe kind of useful as a super unlock!
Yeah.... it isn't supposed to do that
Thanks for the bug report!