Japanese label cannot be displayed on Mapbox

Question

I'm developing an app that displays a map using Mapbox. I use the Flutter framework and mapbox_gl plugin.

I created a Japanese label display style in MapBox Studio and specified the URL in the mapbox_gl plugin. But all the labels disappear. (English label style is displayed normally).

This issue only occurs on Android, not iOS.

  @override
  Widget build(BuildContext context) {
    final String token = "my secret token";
    final String style = "my Japanese style URL";
    return new Scaffold(
      appBar: AppBar(title: Text(widget.title),),
      body: MapboxMap(
        accessToken: token,
        styleString: style,
        initialCameraPosition: getCameraPosition(),
        compassEnabled: true,
        compassViewPosition: CompassViewPosition.TopLeft,
        compassViewMargins: Point(100, 100),
        myLocationEnabled: true,
        myLocationTrackingMode: _trackingMode,
        myLocationRenderMode: MyLocationRenderMode.COMPASS,
        onMapCreated: _onMapCreated,
        onMapLongClick : _onMapLongClick,
        onStyleLoadedCallback: _onStyleLoadedCallback,
        onUserLocationUpdated: _onUserLocationUpdated,
        onCameraTrackingChanged: _onCameraTrackingChanged,
      ),
    );
  }