I cannot reproduce your problem.
TZInfo::Country.all.each do |c| puts "#{c}: #{c.zone_identifiers}" end; shows Australia: ["Australia/Lord_Howe", "Antarctica/Macquarie", "Australia/Hobart", "Australia/Melbourne", "Australia/Sydney", "Australia/Broken_Hill", "Australia/Brisbane", "Australia/Lindeman", "Australia/Adelaide", "Australia/Darwin", "Australia/Perth", "Australia/Eucla"]