ObservableList / ObservableMap not rebuild ui after mutate property

[Poloten]

ChatItem is class without the Store , I attempt to mutate propery in ObservableList and ObservableMap but tracking changes not working. I tried with chatStore.chats.toList() and without toList(), and add observer inside itemBuilder, but nothing happend. UI updating only if i change the route or reassing whole chatsMap / chats. Please can u help me with this simple task.

I also extend ChatItem class with equatable package to override hashCode and operator ==
I use .g generator

mobx: ^2.4.0
flutter_mobx: ^2.2.1+1
mobx_codegen: ^2.6.2

class ChatsStore = _ChatsStore with _$ChatsStore;
abstract class _ChatsStore with Store {

@MakeObservable(useDeepEquality: true)
ObservableList<ChatItem> chats = ObservableList.of([]);
@MakeObservable(useDeepEquality: true)
ObservableMap<String, ChatItem> chatsMap = ObservableMap<String, ChatItem>.of({});
@computed
ObservableList<ChatItem> get computedChatList => ObservableList.of(chatsMap.value);

@action
Future<void> getChats() async {
  List<ChatItem>? chatList = await getChatsList();
  if (chatList == null) return;

  // try List
  chats.clear();
  chats.addAll(chatList);

   // try Map
  chatsMap.clear();
  for (var chat in chatList) {
    chatsMap[chat.id] = chat;
  }
}

/// I tried to update property inside **ChatItem**
@action
updateUnread(String id) {
  print('hash before: ${ chatsMap[id].hashCode}');
  chatsMap[id].unreadCount = 99;
  print('hash after: ${ chatsMap[id].hashCode}'); // hash changed
  
  var found = chats.firstWhere((el) => el.id == id);
  found.unreadCount = 98;
}
}

Widget

Column(children: [
        Expanded(
          child: Observer(builder: (_) {
            var chatList = chatStore.chats.toList();
            print('REBUILD');
            return RefreshIndicator(
                onRefresh: handleRefresh,
                color: Colors.white,
                backgroundColor: Colors.blue,
                child: ListView.separated(
                  separatorBuilder: (_, int index) => const DididerWmKeyVal(),
                  itemCount: chatList.length,
                  itemBuilder: (_, int index) {
                    var element = chatList[index];
                    return InkWell(
                      child: SizedBox(
                        height: 70,
                        child: Row(
                          children: [
                            Container(
                              padding: EdgeInsets.only(top: 10),
                              alignment: Alignment.topCenter,
                              width: 60,
                              child: Stack(
                                children: [
                                  AvatarWidget(wmid: element.id),
                                  BadgeWidget(count: element.unreadCount)
                                ],
                              ),
                            ),
                            Expanded(
                              child: Padding(
                                padding: EdgeInsets.only(top: 4),
                                child: Column(
                                  crossAxisAlignment: CrossAxisAlignment.start,
                                  children: [
                                    Text(element.name),
                                    Text('${element.hint}'.trim()),
                                  ],
                                ),
                              ),
                            ),
                            ListItemTime(time: element.time),
                          ],
                        ),
                      ),
                      onTap: () {
                        chatStore.updateUnread("78000000");
                  },
                ));
          }),
        ),
      ]),