Problem with Spigot 1.8.3 and server.performance.tick_health

[Doridian]

As the title described, I am having a problem with that API call on Spigot 1.8.3.

It always returns elapsedTicks 0, clockRate 0. The other values seem correct (/tps ingame shows the expected results).

array(4) {
  ["result"]=>
  string(7) "success"
  ["success"]=>
  array(7) {
    ["expectedTime"]=>
    int(30000)
    ["elapsedTicks"]=>
    int(0)
    ["expectedTicks"]=>
    int(600)
    ["expectedClockRate"]=>
    float(20)
    ["error"]=>
    float(0)
    ["clockRate"]=>
    float(0)
    ["elapsedTime"]=>
    int(30597)
  }
  ["source"]=>
  string(30) "server.performance.tick_health"
  ["is_success"]=>
  bool(true)
}