No timezones for any location

I cannot set any timezone on my Mac. If I go to Date & Time and pick any location I always get empty timezone.

Running: sudo systemsetup -listtimezones returns Time Zones:

When I try to set timezone from command line I go info about invalid timezone. What is interesting: /etc/localtime -> /var/db/timezone/zoneinfo/Europe/Warsaw

Still time is not correct for Warsaw timezone. I tried set automatically and not - nothing helps. (I did reboot laptop) I suspect there is some cache for timezones which is corrupted, but I don't know how to rebuild it.

System Version: macOS 10.15.6 (19G2021) Kernel Version: Darwin 19.6.0

I think you are encountering the same issue as Time in GMT or Missing Time Zones in systemsetup. I posted a solution there. In my case, I didn't even have the visual representation of the timezone on the map.