RadioButton items not resetting in RecyclerView

Question

This has been asked before but those solutions didn't help me out. I have a RecyclerView that is scrollable and only partially visible on the screen at any one time. It holds a list of RadioButtons and some text related to each item. When you click on a RadioButton, the last button selected prior to this one should turn off. It does not. Each button you click gets selected and the other ones that you selected before stay selected as well.

It's set up like this:

<?xml version="1.0" encoding="utf-8"?>
<androidx.appcompat.widget.LinearLayoutCompat
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:background="@color/white"
    tools:context=".ui.SettingsActivity">


<RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginStart="15dp"
        android:layout_marginTop="5dp"
        android:layout_marginBottom="5dp"
        android:orientation="horizontal">

    <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@string/video_settings"
            android:textColor="@color/black"
            android:textStyle="bold"
            android:textSize="@dimen/clickableTextSize"
            android:layout_alignParentStart="true"
            />
</RelativeLayout>


<androidx.appcompat.widget.LinearLayoutCompat
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:weightSum="100"
        android:gravity="bottom"
        android:orientation="vertical">

    <TextView
            android:layout_width="match_parent"
            android:layout_height="0dp"
            android:layout_weight="15"
            android:paddingStart="15dp"
            android:paddingEnd="15dp"
            android:text="@string/set_resolution_and_fps"
            android:textSize="@dimen/history_text_size"
            android:gravity="center_vertical"
            android:background="@color/grey_200"
            android:textColor="@color/black"
            />

<androidx.recyclerview.widget.RecyclerView
        android:id="@+id/rv_video_resolution"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="80"
        android:layout_marginTop="5dp"/>

<Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/submitVideoSettings"
        android:text="@string/submit"
        android:layout_marginBottom="5dp"
        android:textColor="@color/black"
        android:layout_gravity="center|bottom"

        />

  </androidx.appcompat.widget.LinearLayoutCompat>
</androidx.appcompat.widget.LinearLayoutCompat>

The recycler looks like this:

<?xml version="1.0" encoding="utf-8"?>
<androidx.appcompat.widget.LinearLayoutCompat
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_marginTop="3dp"
    android:orientation="horizontal"
    xmlns:android="http://schemas.android.com/apk/res/android">

<RadioButton
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/resolutionRVRadioButton"
        />
<TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/resolutionRVTV"
        />

<TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="5dp"
        android:text="@string/at_symbol"
        />

<TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/framesPerSecondRVTV"
        android:layout_marginStart="5dp"
        />

<TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/fps"
        />
</androidx.appcompat.widget.LinearLayoutCompat>

The code for the adapter looks like this.

    class ResolutionRVAdapter(private val sharedNavAndMenuViewModel: SharedNavAndMenuViewModel,
                                private val lastResolutionSelected: String,
                                private val capabilityDataList: List<CameraCapabilitySpecificFPS>) : RecyclerView.Adapter<CameraResolutionRVAdapter.ViewHolder>(){
    private var lastCheckedPosition = -1

    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): CameraResolutionRVAdapter.ViewHolder {
        val v =  LayoutInflater.from(parent.context).inflate(R.layout.camera_resolution_recycler_item, parent, false)
        val viewHolder = ViewHolder(v)

        Timber.i("Added viewHolder: ${viewHolder.resolutionText.text}")

        return ViewHolder(v)
    }

    inner class ViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView){
        val resolutionRadioButton : RadioButton = itemView.findViewById(R.id.resolutionRVRadioButton)
        val resolutionText : TextView = itemView.findViewById(R.id.resolutionRVTV)
        val framesPerSecondText : TextView = itemView.findViewById(R.id.framesPerSecondRVTV)
    }

    override fun onBindViewHolder(holder: ViewHolder, position: Int) {
        val child = capabilityDataList[position]
        Timber.i("onBindViewHolder currently working with resolution ${child.resolution} range of $child.range")
        holder.resolutionText.text = child.resolution.toString()
        holder.framesPerSecondText.text = child.fps

        Timber.d("OnBindViewholder and lastResolutionSelected = $lastResolutionSelected")

        if(lastResolutionSelected.isEmpty()) {
            if(position == 0) {
                holder.resolutionRadioButton.isChecked = true
                Timber.i("No last resolution was selected. Setting index 0 to true")
            }
        } else if(lastResolutionSelected == holder.resolutionText.text.toString()) {
            Timber.i("An old resolution of ${holder.resolutionText.text} was selected. Setting index $position to true")
            holder.resolutionRadioButton.isChecked = true
        }

        holder.resolutionRadioButton.setOnClickListener {
            Timber.i("Index hit was: $position resolution at that index was: ${holder.resolutionText.text}")

            if(holder.resolutionRadioButton.isChecked) {
                //Button was already checked...must be the same button hit before...nothing to do
            } else {
                holder.resolutionRadioButton.isChecked = true
                runOnUiThread {
                    notifyItemChanged(lastCheckedPosition)
                    notifyItemChanged(position)
                }

                lastCheckedPosition = position
            }
        }
    }

    override fun getItemCount(): Int {
        return capabilityDataList.size
    }
   }

Can anyone tell me what it is I'm doing wrong?