https://codesandbox.io/s/upbeat-frost-3tt25

1. Press Suspend, see "Loading..."
2. Wait five seconds, you'll see "Happy birthday" at some point 
3. You won't see it again no matter how long you wait

Expected: you'll see it every five seconds.
Scheduler.unstable_yieldValue('Foo');
      return (
        <Suspense fallback={<Text text="Initial load..." />}>
          <Suspense
            unstable_avoidThisFallback={true}
            fallback={<Text text="Loading A..." />}>
            <Text text="A" />
            {showB ? (
              <Suspense
                unstable_avoidThisFallback={true}
                fallback={<Text text="Loading B..." />}>
                <AsyncText text="B" ms={5000} />
              </Suspense>
            ) : null}
          </Suspense>
        </Suspense>
      );
    }
    ReactNoop.render(<Foo />);