I'm having similar problem to the timezone being empty.
Running LM14_64, TB17.0, and Lightning 1.9. My calendar events are not showing up in the right time. Going to Preferences -> Calendar -> Timezones, I can't select anything.
I even tried from within a new appointment, Options -> Show Timezones, and tried selecting from there. No luck. It shows the map with UTC/GMT highlighted, and I can't change it.
I'm running the exact same TB/Lightning versions on my Ubuntu 12.04 laptop, and do not have the same problem. Which is why I'm thinking this is Mint14(or 12.10?) specific issue.
FWIW: The date/time/timezone is correct (and changeable) on the Mint/Cinnamon settings, just fine.
SOLVED IT! I forgot about the manual config in Mozilla products
...I went into Prefernces -> Advanced -> General/Config Editor. Changed the calendar.timezone.local to "America/New_York" Doesn't solve the weirdness completely, but gets around it for sure!