There have been several bug reports and feature requests regarding wrongly tracked working hours during sleep/hibernate and even power off. I think the main problem is that WorkingHours cannot listen for events while the App is not running. Therefore, stop/start timer does not work in all cases (the stop is never performed).
During sleep/hibernate and power off, there is clearly no activity (mouse movement and keyboard events) and therefore, this time should not be tracked if stop timer during inactivity is set. Probably, the App needs to remove the wrongly detected active time during sleep by observing that there have not been any activity events in hindsight, after wakeup.
My use case: I would like WorkingHours to start automatically at boot and keep it running forever. During all inactivities, the timer should stop and during activities, it should run. No matter if the inactivities are caused by shutdown, sleep, hibernate or real inactivities because of absent mouse movements or keyboard input.