State change does not trigger UI update on flutter bloc - flutter

Question

I'm currently trying to implement some basic bluetooth scanning functionality using flutter_reactive_ble to an App.
I'm also using flutter bloc for state management.
Now I have to Problem, that I find multiple bluetooth devices, but the UI doesn't get updated. When I'm using print commands track whats going on, I see the state updates correctly, but the UI is only updated once.
Here is the BLoc:
class BtConnectionBloc extends Bloc<BtConnectionEvent, BtConnectionState> {
final BtConnectionsRepository _repo;
late StreamSubscription _stream;
BtConnectionBloc(this._repo) : super(const DevicesState()) {
List<DiscoveredDevice> _devices = [];
on<StartScanningEvent>((event, emit) {
_stream = _repo.getDevices().listen((device) {
final knownDeviceIndex = _devices.indexWhere((d) => d.id == device.id);
if (knownDeviceIndex >= 0) {
_devices[knownDeviceIndex] = device;
} else {
_devices.add(device);
add(FoundDevices(deviceList: _devices));
}
});
});
on<EndScanningEvent>((event, emit) {
_stream.cancel();
_devices = [];
emit(const DevicesState());
});
on<FoundDevices>((event, emit) {
emit(DevicesState(deviceList: _devices));
});
}
}
And this is the repository class I've created:
class BtConnectionsRepository {
final PairedDevicesRepository _deviceRepo = PairedDevicesRepository();
final FlutterReactiveBle _ble = FlutterReactiveBle();
static BtConnectionsRepository get instance => BtConnectionsRepository();
Stream<DiscoveredDevice> getDevices() async* {
yield* _ble.scanForDevices(withServices: []);
}
void connectToSavedDevices() async {
PairedDevices _devices = await _deviceRepo.getPairedDevices();
for (SavedDevice device in _devices.savedDevices) {
_ble.connectToDevice(id: device.id);
}
}
}
On the UI Part, i'm adding an event in the didChangeDependencies override, with
context.watch<BtConnectionBloc>().add(StartScanningEvent());
and the specific UI part is:
BlocBuilder<BtConnectionBloc, BtConnectionState>(
buildWhen: (previousState, state) {
if(previousState.props.length != state.props.length){
return true;
}
else {
return false;
}
},
builder: (context, state) {
return Container(
width: MediaQuery.of(context).size.width,
padding: EdgeInsets.symmetric(
horizontal: MediaQuery.of(context).size.width * 0.0826,
),
child: createDeviceList(state.props));
},
)
The function called there looks like this:
Widget createDeviceList(List<DiscoveredDevice> devices) {
List<Widget> deviceWidgetList = [];
for (var device in devices) {
deviceWidgetList.add(PairingItem(
device: device,
onPressed: () {},
));
}
return Column(children: deviceWidgetList);
}
I'm pretty clueless why it behaves like this, but I only get like the first update, showing a few devices, but every device found a bit later does not show up or causes an UI update.

Answer 1

After lots of searching and trying, I've found the answer myself.
The Events / States of the Bloc extended Equatable, which caused the bloc not to refresh on emitting an updated state instead of a different state.