This state typically shows up when the system has brought up some UI in front of the app, such as the Wi-Fi selection dialog. The events in question are UI events; the app is still in the foreground and thus timers and so on are still running.
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Quinn “The Eskimo!”
Apple Developer Relations, Developer Technical Support, Core OS/Hardware
let myEmail = "eskimo" + "1" + "@apple.com"
Thanks very much Quinn. (Just for other readers, which is in line with Quinn's answer, we also see this when a Touch ID prompt is being displayed.)