BLE connect and services

Connectivity BLE // NFC
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1

Goodday

I have asked this already here but see it does not show up . I may have tagged it incorrectly (BLE service + connect not working on all devices)

The code below is based on the HTM example. But I have noticed it does not run on Xenons and only on some Argons. Im using nRF connect to test.

#include "Particle.h"

float battVoltage;//holds the local battery voltage
SerialLogHandler logHandler(LOG_LEVEL_TRACE);

const unsigned long UPDATE_INTERVAL_MS = 2000;
unsigned long lastUpdate = 0;
float getTempC();
uint32_t ieee11073_from_float(float temperature);

const char* xenonBattService = "b4250400-fb4b-4746-b2b0-93f0e61122c6"; //service
BleUuid xenonBattBleService(xenonBattService);
BleCharacteristic batteryMeasurementCharacteristic("bat", BleCharacteristicProperty::NOTIFY, BleUuid(0x2A19), xenonBattService);

void setup() {

  (void)logHandler; // Does nothing, just to eliminate the unused variable warning
  BLE.on();
  //BLE.setAdvertisingTimeout(500); // 1000 * 10 ms // time period of the the detonation period (how long it get transmitted)
  Particle.keepAlive(20);
  Serial.begin(115200);
  
  pinMode(BATT, INPUT); // argon battery 
  BLE.setTxPower(0); // Use lower power // Use lower power -20, -16, -12, -8, -4, 0, 4, 8.
  // set initial IO states
  
  pinMode(BATT, INPUT);

    BLE.addCharacteristic(batteryMeasurementCharacteristic);
    BleAdvertisingData advData;
    advData.appendServiceUUID(xenonBattService);
    BLE.advertise(&advData);
}
void loop() {
    if (millis() - lastUpdate >= UPDATE_INTERVAL_MS) {
        lastUpdate = millis();

       if (BLE.connected()) {
            uint8_t buf[6];
              battVoltage = analogRead(BATT) * 0.0011224;
            //battVoltage = analogRead(BATT) * 0.0011224 / 3.7 * 100; /// in percentage
             buf[0] = 0x01;
             memcpy(&buf[1], &battVoltage, 5);
             batteryMeasurementCharacteristic.setValue(buf, sizeof(buf));

       }
    }
}

When I run the code on Xenons and try to conenct I get
Invalid handle
BLE_HCI_CONN_FAILED_TO_BE_ESTABLISHED
BLE_HCI_REMOTE_USER_TERMINATED_CONNECTION

Is this normal?