Nested Flutter Futurebuilder is not updating the view - flutter

Question

I have a Stateful widget that I am displaying inside a stateless widget. I have reused this Widget in several parts of my application, where it worked.
The widget looks a somethin like this
class InnerWidget extends StatefulWidget {
// private keys for objects in the remote dataahase
List<int> privateKeys;
const InnerWidgt({
Key key,
this.privateKeys,
}) : super(key: key);
#override
_InnerWidgetState createState() => _InnerWidgetState();
}
class _InnerWidgetState extends State<InnerWidget> {
// data retrieved from the database
Future<List<SomeClass>> data;
#override
void initState() {
this.data = this.fetchData(widget.privateKeys);
super.initState();
}
#override
Widget build(BuildContext context) {
return FutureBuilder<List<SomeClass>> (
future: this.data,
builder: (BuildContext contest, AsyncSnapshot<List<SomeClass>> snapshot) {
if(snapshot.hasData){
// return a widget (a list of names in this case)
}
return Text('Loading...');
}
);
}
Future<List<SomeClass>> fetchData(List<int> pKeys){
// fetches the JSON objects from the server and returns them as instances
}
}
The widget is created and given a list of keys, it makes a call to the remote API to get some objects and displays them in a list. I thought it might be nice that this widget is kind of handling itself, but maybe it's bad design?
What happens, is that the fetchData() method is never called and the "Loading..." is displayed forever. However snapshot.hasData does return true, so I'm thinking this is some kind of repainting issue.
The view I am talking about, where this is used is a detail view, which you navigate to from a list (ListView). I am using this exact same InnerWidget in the the elements inside the ListView, where it works perfectly fine. But when I click on the item to navigate to the detail page, the same InnerWidget does not work. (I know fetching the same data twice is not good, I have that in the back of my head to change it, and there's already a Cache underneath). Maybe this has something to do with the preserved state in the ElementTree? That because I am using the same InnerWidgit, it's preserving its state and not rerendering?
I hope I phrased my question well enough, I did not want to throw hundreds of lines of code at you, that's why created this minimal example of the widget at least. I can add the list and navigation part too if needed, but maybe this is something, that somebody that has worked more with Flutter, knows right away, I'm only 3 weeks in.