connect_flag doesn't re-establish itself

In my sketch I am monitoring the connect_flag and drive a physical LED either green or red if connected (depending on a zone control in my RemoteXY app), and blue if not connected.  That all woks OK, the LED turns blue if I put the iPad app into the background. Serial comms to the Bluetooth module stops, as expected, and the "paired" led on the BT module stays solid.

However, when I bring the RemoteXY app to the foreground again, serial comms restarts, indicating that it is communicating with the iPad app again, but the connect_flag remains 0, meaning I have to Stop the project and restart it manually.  You can see from the code excerpt that I have put some debugging outputs for my oscilloscope, and can clearly see scope1 toggling on and off, but not scope2

Has anyone else seen this behaviour, and more importantly know a way round it ?

void loop() {
  digitalWrite(scope1, HIGH); 
  RemoteXY_Handler ();
  digitalWrite(scope1, LOW); 

if (RemoteXY.connect_flag == 0) {
  // not connected
  LED_Blue();
//   delay(5);
  }
else {
  // connected
  digitalWrite(scope2, HIGH); 
  switch (RemoteXY.ZONE) {
    // ZONE = 0, so Zone 1
    case 0:
     LED_Green();
     RemoteXY.led_1_g = 150;
     RemoteXY.led_1_r = 0;
     digitalWrite(IR2_Gate, LOW);
     digitalWrite(IR1_Gate, HIGH);
     break;

    case 1:
     // ZONE = 1, so Zone 2
     LED_Red();
     RemoteXY.led_1_r = 150;
     RemoteXY.led_1_g = 0;
     digitalWrite(IR1_Gate, LOW);
     digitalWrite(IR2_Gate, HIGH);
     break;
  }
  digitalWrite(scope2, LOW); 
}