FullScreenIntent not working on xiaomi devices

I am developing a calling app. I need to show the ringing screen automatically after receiving push notification. It works ok except xiaomi-devices. Sometimes, the screen is not switched on. What is the secret for xiaomi-devices?
All permissions on the xiaomi-device are granted:

1. Background processes: no limit
2. Disabled battery optimizations
3. Autostart is on

What i use programmatically:

1.

NotificationCompat.Builder()
 .setPriority(NotificationCompat.PRIORITY_HIGH)
 .setCategory(NotificationCompat.CATEGORY_CALL)
 .setFullScreenIntent(fullScreenPendingIntent, true)

 private fun showWhenLockedAndTurnScreenOn() {

        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O_MR1) {
            setShowWhenLocked(true)
            setTurnScreenOn(true)
            val keyguardManager = getSystemService(KEYGUARD_SERVICE) as KeyguardManager
            keyguardManager.requestDismissKeyguard(this, null)
        } else {
            window.addFlags(
                WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON or
                        WindowManager.LayoutParams.FLAG_DISMISS_KEYGUARD or
                        WindowManager.LayoutParams.FLAG_SHOW_WHEN_LOCKED or
                        WindowManager.LayoutParams.FLAG_TURN_SCREEN_ON
            )
        }
    }

3. Manifest permissions:

for activity:

 android:showOnLockScreen="true"

for app:

<uses-permission android:name="android.permission.WAKE_LOCK" />
<uses-permission android:name="android.permission.USE_FULL_SCREEN_INTENT" />

What am I missing out for Xiaomi?

it seems that this code helped:

  fun asquireWake() {
    val mPowerManager = getSystemService(Context.POWER_SERVICE) as PowerManager
    val mWakeLock: PowerManager.WakeLock = mPowerManager.newWakeLock(
        PowerManager.SCREEN_BRIGHT_WAKE_LOCK or PowerManager.ACQUIRE_CAUSES_WAKEUP,
        "App:IncomingCall"
    )
    mWakeLock.acquire(1*60*1000L /*1 minute*/)
}

I writed it before showing the notification.

Xiaomi devices have a specific permission regarding full screen intents on the lock screen. You have to enable this permission manually:

1. Go to app settings and select Other permissions:

2. Select Show on lock screen:

3. Check Always allow on the pop-up:

This setting will ensure that your app displays full screen intent activities on the lock screen.