timing(..).start() seems broken

Hey team, I have a pretty simple example of Animated.timing.start that doesn’t work. In my application, it fails silently, but these repros also demonstrate:

Repro Snippet

export default class App extends React.Component {
  state = { progress: new Animated.Value(0.15) };
  componentDidMount() {
    // this should cause the message to fade in, but it does not
    Animated.timing(this.state.progress, {
      toValue: 1,
      duration: 500,
      easing: Easing.out(Easing.cubic)
    }).start(() => {
      // this should get called after ~500ms, but it does not
      console.log("Transition complete");
    });
  }
  render() {
    return (
      <Animated.View
        style={[{ opacity: this.state.progress }, styles.container]}
      >
        <Text style={styles.paragraph}>Hello Reanimated</Text>
      </Animated.View>
    );
  }
}

Snack (crashes expo)

https://snack.expo.io/rkIOPnLzV

Native Repo (crash tested on iOS)

https://github.com/ericvicenti/reanimated-bug

[kantorm]

@ericvicenti Try to use Easing from react-native-reanimated

[ericvicenti]

I’m going to close this for now because I can’t find a simple way to reproduce the issue… I’ll re-file if I pin it down