Works One One Android Device But Not Another

I just watched a Youtube video - HC-05 Bluetooth Module with Arduino-MIT App Inventor (

Followed the directions to build a simple sketch for an Arduino Uno to turn an LED off and on via Bluetooth using an HC05. Initially created it for my phone (Samsung A53 Android 13). When I got to the point in the app to Connect, it showed me an empty black screen with no available Bluetooth devices. Uninstalled it, built a new QR code, unpaired the HC05, re-paired it and re-installed the app. No change.
Then I changed the app only to be Tablet size instead of Phone size, built a new QR code and installed it on my old Samsung Tablet A running Android 7.1.1. It worked flawlessly. Pressed Connect and it showed all available Bluetooth devices. Selected the HC05 and it connected. Was then able to use the app to turn the Arduino mounted LED on and off using the app - as expected.
Is this an issue with Android versions??

char Incoming_value = 0;
void setup() 
  pinMode(13, OUTPUT);       

void loop()
  if(Serial.available() > 0)  
    Incoming_value =;      
    if(Incoming_value == '1')             
      digitalWrite(13, HIGH);  
    else if(Incoming_value == '0')       
      digitalWrite(13, LOW);   

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Thank you! Works perfectly now!!

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