ZM is happily logging motion events with the correct date & time. However, if there's a signal loss, it logs it with a date/time in 1970 (which IIRC is what a zero equates to in UNIX time).
Is this a config thing, something camera specific (although it's hard to see how, by definition on signal loss the time/date has to come from the system).
It really messes timelines up.