Why submitList function of ListAdapter is not working?

Question

I'm pretty sure that my list has changed but the view not updated I'm using submitList like this:

recentChatsAdapter.submitList(recentChats?.let { ArrayList<Conversation>(it) })

DiffUtil code:

class ChatDiffUtil: DiffUtil.ItemCallback<Conversation>() {

    override fun areItemsTheSame(oldItem: Conversation, newItem: Conversation): Boolean {
        return oldItem.chatId == newItem.chatId
    }

    override fun areContentsTheSame(oldItem: Conversation, newItem: Conversation): Boolean {
        return oldItem == newItem
    }
}

I saw this question and this one

but I didn't find any solution to my problem.