Adding an item to a mutable list at index zero doesnt update the recyclerview

I have a recyclerview inside a fragment that displays a mutable list of tasks that each have a title and description, wrapped in mutable live data.

private val _tasks = MutableLiveData<MutableList<Task>>()

To add those items, i implemented a bottom sheet dialog fragment with text edits for both values.

When i add a task item without specifying the index the recyclerview updates correctly :

_tasks.value!!.add(Task(taskEditText,descriptionEditText))

However, when i specify i want the new task item at index 0 and i add multiple task items, the recyclerview displays the first task i added over and over.

Things i've tried:

Using notifyDataSetChanged inside the adapter works and updates the recyclerview correctly, however i tried adding it to my add task button inside my bottom sheet dialog and it does nothing.

I tried adding the items to a temporary list and then setting it to _tasks.value but the same thing happened, only updates when i dont specify the index.

Here are relevant files :

AddTaskFragment (Bottom Sheet Dialog) :

override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
    super.onViewCreated(view, savedInstanceState)
    binding.lifecycleOwner = viewLifecycleOwner
    // if the textfields are not empty, adds the task and leaves the dialog
    binding.buttonAdd.setOnClickListener{
        if (binding.addTaskEditText.text!!.isNotEmpty() && binding.addDescriptionEditText.text!!.isNotEmpty()) {
            viewModel.addTask(binding.addTaskEditText.text.toString(), binding.addDescriptionEditText.text.toString())
            dismiss()
        }
    }
}

addTask function inside viewmodel :

fun addTask(taskEditText : String, descriptionEditText : String) {
    _tasks.value!!.add(0,Task(taskEditText,descriptionEditText))
}

Adapter:

override fun onBindViewHolder(holder: ViewHolder, position: Int) {
    val task = viewModel.tasks.value!![position]
    holder.itemTitle.text = task.text
    holder.itemDescription.text = task.description
    holder.textViewOptions.setOnClickListener {
        onMenuClick(position, holder, task)
    }
}

Thanks in advance and i hope you pros can help me

viewModel.tasks.observe(viewLifecycleOwner, Observer {
            adapter.notifyDataSetChanged()
        })

Try it.