Why is performFiltering() called twice in custom AutocompleteTextview adapter

Question

I created a custom AutoCompleteTextView adapter. The first time performFiltering() is called, it filters the results and returns an instance of FilterResults (with the correct values). The PublishResults() method is called afterward by the system, which calls notifyDataSetChanged().

Immediately after the call to notifyDataSetChanged(), the performFiltering method is called again. After returning its results, it does not call PublishResults() again.

I should also note that the filtered results are NOT delivered to the AutoComplete widget. Instead, the entire raw data set is shown in the dropdown list. And it may be worth noting that even though I have a threshold on the widget set to 2, performFiltering() is called after the first character is entered.

So my questions are: (1) why is performFiltering() called a second time after notifyDataSetChanged() ?, (2) why is performFiltering() called before Threshold is met?, and (3) what are the most common reasons for the filtered results not making it into the dropdown list?

import android.content.Context;
import android.util.Log;
import android.view.View;
import android.view.ViewGroup;
import android.view.LayoutInflater;
import android.widget.BaseAdapter;
import android.widget.Filterable;
import android.widget.Filter;
import android.widget.TextView;

import java.util.ArrayList;

/**
 * Created by John on 12/31/2016.
 */

public class myContactsAutoCompleteAdapter extends BaseAdapter
                                            implements Filterable {

    Context context;
    private LayoutInflater inflator;
    private ArrayList<Contacts.ContactDataRow> contactsList;
    private ArrayList<Contacts.ContactDataRow> suggestions = new ArrayList<>();

    public myContactsAutoCompleteAdapter(Context ctx, ArrayList<Contacts.ContactDataRow> data ) {
        this.context = ctx;
        this.contactsList = data;
        this.inflator = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    }

    @Override
    public int getCount() {
        return contactsList.size();
    }

    @Override
    public Object getItem(int position) {
        return contactsList.get(position);
    }

    @Override
    public long getItemId(int position) {
        return position;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        ViewHolder viewHolder;
        if (convertView == null) {
            convertView = inflator.inflate(R.layout.contacts_listview_item, null);
            viewHolder = new ViewHolder();
            viewHolder.txt_name = (TextView) convertView.findViewById(R.id.txt_contact_name);
            viewHolder.txt_phone = (TextView) convertView.findViewById(R.id.txt_contact_phone);
            viewHolder.txt_phonetype = (TextView) convertView.findViewById(R.id.txt_contact_type);
            convertView.setTag(viewHolder);
        } else {
            viewHolder = (ViewHolder) convertView.getTag();
        }
        viewHolder.txt_name.setText(contactsList.get(position).displayName);
        viewHolder.txt_phone.setText(contactsList.get(position).phone);
        viewHolder.txt_phonetype.setText(contactsList.get(position).phoneType);

        return convertView;
    }

    private static class ViewHolder {
        TextView txt_name;
        TextView txt_phone;
        TextView txt_phonetype;
    }

    @Override
    public Filter getFilter() {
        return new ContactsAutocompleteFilter();
    }

    private class ContactsAutocompleteFilter extends Filter {

        @Override
        protected FilterResults performFiltering(CharSequence constraint) {

            FilterResults filterResults = new FilterResults();

            if (constraint != null && constraint.length() >= 2) {
                suggestions.clear();

                //Check for similarities in data from constraint
                for (Contacts.ContactDataRow row : contactsList) {
                    if (row.displayName.toLowerCase().contains(constraint.toString().toLowerCase())) {
                        suggestions.add(row);
                    }
                }

                filterResults.values = suggestions;
                filterResults.count = suggestions.size();
            }

            return filterResults;

        }

        @Override
        protected void publishResults(CharSequence constraint, FilterResults results) {
            if (results != null && results.count > 0) {
                notifyDataSetChanged();
            } else {
                notifyDataSetInvalidated();
            }
        }
    }
}

EDIT: I updated this to include the entire adapter class