It should show up once you unplug the phone from a full charge, but the moment you respring or reboot after that, that box will show up blank.
It's not a bug. Stop respringing.
When your phone is fully charged, your usage time resets. When you respring, the stats go blank until you fully charge again.
Same problem here, jailbroken ipod touch 3rd Gen (iOS 5.0.1 with "Usage Stats 4 iOS" addon). All usage stats blank. Don't know if it's got anything to do with it, but battery only seems to charge to 90 odd percent, not the full 100%.
And all my LowBatteryLogs show: Awake Time 00:00:00, Standby Time 00:00:00.