And what would that mean, then? I don't think the sentence makes sense in English, so it's hard to translate it.
"Żaden pracownik nie nie pracuje" would make about the same sense - not much.
"Żaden pracownik się nie obija" would make sense. "obijać się" is a colloquial verb meaning 'to get lazy, not to work' when you actually are supposed to do something.
It does work in english, "no employee is not working" would be quite standard a way of defending one's employees (at least in british or irish english) if they were accused of being lazy for example.
Although i understand how "the employees are working" is also acceptable (and in the case of polish the more direct transliteration), it is less dramatic and carries less emphasis.
It is a strange one, when you translate word for word and as a result, you loose the meaning completely, and... you will not be understood.
It is very useful to think of the word "żaden" (singular masculine) as a singular masculine noun negation:
żaden/ani jeden pracownik - no employee/not a single employee
There is a double negation in the Polish sentence, but to convey the same thought, it is enough to have just one in the English one. Once you translate "Żaden pracownik" into "No employee" you just follow the English grammar and put the verb without negation: Żaden pracownik nie pracuje - No employee works/is working