Time Zone shows (null) with UTC+0 offsets on all timezones

I'm new to Linux and I'm having an issue with my clock showing the wrong time. When I pull up the Date & Time setting, my Time Zone shows

(null) (Los Angeles, United States)

If I turn off Automatic Time Zone and pull up the world map, every timezone displays

(null) (UTC+00) ...

If I click on the zone again, it updates with the correct timezone offset; however, the setting does not stay and eventually becomes null again. Entering date from the command-line shows the wrong time as well. date +%Z shows a blank. What can I check or run to resolve?

My system is Ubuntu 18.04.1 LTS

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