ObservableList's change not being listened to

[hydroper]

Minimal Reproduction

pubspec.yaml:

name: observable_demo

dependencies:
  observable: ^0.24.0

Dart:

import 'package:observable/observable.dart';

void main() {
  var obs = ObservableList.from(["first value"]);
  obs.changes.listen(([value = ""]) {
    print(value);
  });
  obs[0] = "second valuee";
}

Expected Behavior

Print:

second valuee

Current Behavior

Prints nothing.