I used hour bars just to test how BarZone behaves, to better understand it. Even the logfile still has the first bar at 15:00 with BarZone set to EST, same as with BarZone set to UTC.

Perusing the manual, I found a line in the release history, which says "The BarZone variable can be used to shift daily bars to a certain local time zone." So I guess this feature is designed only for daily bars. Then it makes sense that hourly bars don't work.