RecyclerView not filtering records with search

I am using RecyclerView extending from ListAdapter and implementing Filterable interface as below.

class GroceryListAdapter(private val mContext: Context, private val viewModel: MainViewModel, groceryList: List<Grocery>) :
    ListAdapter<Grocery, GroceryListAdapter.GroceryViewHolder>(GroceryDiffUtils()), Filterable {
    var groceryListFull : MutableList<Grocery> = groceryList.toMutableList()
    ...
    ...
    override fun getFilter(): Filter {
        return ExampleFilter()
    }
    
    inner class ExampleFilter() : Filter() {
        override fun performFiltering(constraint: CharSequence?): FilterResults {
            val filteredList = mutableListOf<Grocery>()
            if (constraint.isNullOrEmpty())
                filteredList.addAll(groceryListFull)
            else {
                val filterPattern = constraint.toString().lowercase().trim()
                for (item in groceryListFull) {
                    if (item.name.lowercase().contains(filterPattern))
                        filteredList.add(item)
                }
            }

            val results = FilterResults()
            results.values = filteredList
            return results
        }

        override fun publishResults(constraint: CharSequence?, results: FilterResults?) {
            groceryListFull.clear()
            groceryListFull.addAll(results?.values as MutableList<Grocery>)
            notifyDataSetChanged()
        }

    }

}

and inside fragment, binding results as follows:

        ...
        ...
         viewModel.getGroceryList().observe(viewLifecycleOwner) {
            binding.rvGroceryList.apply {
                adapter = GroceryListAdapter(requireActivity(), viewModel, it)
                layoutManager = LinearLayoutManager(activity?.baseContext!!)
                (binding.rvGroceryList.adapter as GroceryListAdapter).submitList(it)
            }
        }

        binding.groceryItemSearch.setOnQueryTextListener(object : SearchView.OnQueryTextListener {
            override fun onQueryTextSubmit(query: String): Boolean {
                return false
            }

            override fun onQueryTextChange(newText: String): Boolean {
                (binding.rvGroceryList.adapter as GroceryListAdapter).filter.filter(newText)
                return false
            }
        })

When I tried searching, list is not getting filtered. I debugged the filter code adapter, it is working as expected, but not seeing visual changes in the list. What am I missing?