Android Progress bar inside menu item is not updating properly

Question

I have two sensor connected with my android app. Both apps are connecting over BLE and I get two types of data from these sensors.

1. Sensor Data
2. Power Value

To show the power status, I followed a tutorial to create the progressbar inside actionbar menu as follows.

theme.xml
<!-- Power Progress Theme -->
<style name="PowerProgressBar">
    <item name="android:indeterminateOnly">false</item>
    <item name="android:progressDrawable">@drawable/ic_action_power_progress</item>
</style>


layout_power_progress.xml
<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_height="wrap_content"
    android:layout_width="wrap_content"
    style="@android:style/Widget.ActionButton">
    <ProgressBar
        android:id="@+id/powerProgress"
        style="@style/PowerProgressBar"
        android:layout_width="24dp"
        android:layout_height="24dp"
        android:visibility="visible"
        android:layout_gravity="center" />
</FrameLayout>


 menu/main.xml 
 <item
        android:id="@+id/action_power_sensor_1"
        android:title="@string/action_power_sensor_1"
        app:actionLayout="@layout/layout_power_progress"
        app:showAsAction="always" />

<item
        android:id="@+id/action_power_sensor_2"
        android:title="@string/action_power_sensor_2"
        app:actionLayout="@layout/layout_power_progress"
        app:showAsAction="always" />

override fun onPrepareOptionsMenu(menu: Menu?): Boolean {  

    /*---------- Sensor 1 ---------------*/
    sensor1PowerProgressView = menu?.findItem(R.id.action_power_sensor_1)?.actionView?.findViewById(R.id.powerProgress)  
    sensor1PowerProgressView ?.max = 5
    sensor1PowerProgressView ?.progress = sensor1Power 

    /*---------- Sensor 2 ---------------*/
    sensor2PowerProgressView = menu?.findItem(R.id.action_power_sensor_2)?.actionView?.findViewById(R.id.powerProgress)  
    sensor2PowerProgressView ?.max = 100
    sensor2PowerProgressView ?.progress = sensor2Power 

    return super.onPrepareOptionsMenu(menu)
}


/*--- Code where the power is getting updated ----*/
sensorViewModel.getSensor1Power().observe(this) {
        sensor1Power = it 

        if (sensor1PowerPrev!=sensor1Power) {
            sensor1PowerPrev = sensor1Power 
            invalidateOptionsMenu() 
        }
}

sensorViewMode2.getSensor2Power().observe(this) {
        sensor1Power = it 

        if (sensor2PowerPrev!=sensor2Power) {
            sensor2PowerPrev = sensor2Power 
            invalidateOptionsMenu() 
        }
}

I am updating these power values from sensorViewModel. I see the values inside the sensorViewModel getting updated properly upon sensor connect and disconnect. I am logging both values (sensor1Power & sensor2Power ) inside the onPrepareOptionsMenu and I see the values getting logged there properly.

Now after spending whole 2 weeks on this issue I can't figure out why sensor1PowerProgressView and sensor2PowerProgressView are not getting updated on disconnect. They retain the last value.

Anyone, can point out what am I doing incorrectly. if you need any more details, I can share upon request.