logtrail: In logtrail.json, change "timezone" field to another value than "UTC" raise an error

In logtrail.json, if I set "timezone": "Europe/Paris", I get the following error each time logtrail plugin posts a search request :

Error while executing search { [Error: [parse_exception] failed to parse date field [1478552461000] with format [epoch_millis]]
  status: 400,
  message: '[parse_exception] failed to parse date field [1478552461000] with format [epoch_millis]',
  path: '/logstash-*/_search',
  query: { size: 500 },
  body:
   { error:
      { root_cause: [Object],
        type: 'search_phase_execution_exception',
        reason: 'all shards failed',
        phase: 'query_fetch',
        grouped: true,
        failed_shards: [Object] },
     status: 400 },
  statusCode: 400,
  response: '{"error":{"root_cause":[{"type":"parse_exception","reason":"failed to parse date field [1478552461000] with format [epoch_millis]"}],"type":"search_phase_execution_exception","reason":"all shards failed","phase":"query_fetch","grouped":true,"failed_shards":[{"shard":0,"index":"logstash-2016.11.05","node":"sD0Fz592SCmmMebQHT4sTQ","reason":{"type":"parse_exception","reason":"failed to parse date field [1478552461000] with format [epoch_millis]","caused_by":{"type":"illegal_argument_exception","reason":"Invalid format: \\"1478552461000\\""}}}]},"status":400}',
  toString: [Function],
  toJSON: [Function] }