[Flutter] Why does the group field(label) remain empty when I insert a new contact?

I want to add a new contact and specify the group argument. With this piece of code and according to the result of the print() command, everything seems correct, but when I refer to the created contact, I notice that the field group (label) is empty.

My code:

import 'package:flutter/material.dart';
import 'package:flutter_contacts/contact.dart';
import 'package:flutter_contacts/flutter_contacts.dart';

class InsertContact extends StatefulWidget {
const InsertContact({super.key});

@override
State<InsertContact> createState() => _InsertContactState();
}

class _InsertContactState extends State<InsertContact> {

@override
void initState() {
super.initState();
_insertContact();
}

Future<void> _insertContact() async {
if (!await FlutterContacts.requestPermission()) {
} else {
final newContact = Contact()
..displayName ='Ehsan Zarei'
..name.first = 'Ehsan'
..name.last = 'Zarei'
..phones = [Phone('123456789')]
..groups= [Group('444', 'Edu')];
await newContact.insert();
print(newContact);
}

}

@override
Widget build(BuildContext context) {
return const Placeholder();
}
}


console result:

I/flutter ( 7976): Contact(id=, displayName=Ehsan Zarei, thumbnail=null, photo=null, isStarred=false, name=Name(first=Ehsan, last=Zarei, middle=, prefix=, suffix=, nickname=, firstPhonetic=, lastPhonetic=, middlePhonetic=), phones=[Phone(number=123456789, normalizedNumber=, label=PhoneLabel.mobile, customLabel=, isPrimary=false)], emails=[], addresses=[], organizations=[], websites=[], socialMedias=[], events=[], notes=[], accounts=[], groups=[Group(id=444, name=Edu)])


result in device:

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