Refresh indicator in wrong location with CustomScrollView/SliverAppBar

[ultimate-tester]

First of all thank you for creating such a wonderful package. I am having some trouble though with getting it to work for me.
I have a CustomScrollView with a SliverAppBar and a SliverList. For the SmartRefresher, I am using the WaterDropMaterialHeader header. To show a simplified version of the code, it is shown below:

@override
Widget build(BuildContext context) {
	return Scaffold(
		body: SmartRefresher(
			header: const WaterDropMaterialHeader(),
			child: CustomScrollView(slivers: <Widget>[
				SliverAppBar(...),
				SliverList(...),
			]),
		)
	);
}

The problem is that the refresh-widget starts at the very top of the screen, instead of below the SliverAppBar. This means the WaterDropMaterialHeader is shown overlapped on top of the app bar as shown in the below screenshot:

I changed the background colors to show the overlap more clearly.

Perhaps I am using the package wrong, which is why I came here to ask for advice. It would be very great if you can steer me in the correct direction. Thanks in advance!

[worldwidee]

same here, any solution?

[yangjiamu]

same, any solution?