ESP32 BLE iBeacon Arduino Wrong Signal

When I use my ESP32 to emit a BLE iBeacon signal there seems to be something wrong with the signal. It emits a bluetooth signal, but it's not recognized as an iBeacon signal.

I have an ESP32 Wroom32 DevKit V1 / ESP32-D0WD-V3 (revision v3.0), use the Arduino IDE with the board manager set to V2.0.7. The device is bare and completely new.

Don't know if it's relevant, but some times there is a warning that the frequency of the crystal is off: WARNING: Detected crystal freq 41.01MHz is quite different to normalized freq 40MHz. Unsupported crystal in use? Crystal is 40MHz

I tried the default ESP32 iBeacon Arduino demo sketch below. This and other attempts all result in the same; the upload succeeds fine, the serial output is fine, and ESP32 emits a bluetooth signal, but isn't recognized as an iBeacon (or beacon of any kind) like shown in the screenshot of the nRF Connect app.

Can some one spot what I might be missing here?

#include <BLEDevice.h>
#include <BLEServer.h>
#include <BLEUtils.h>
#include <BLE2902.h>
#include <BLEBeacon.h>

#define DEVICE_NAME            "ESP32"
#define SERVICE_UUID           "7A0247E7-8E88-409B-A959-AB5092DDB03E"
#define BEACON_UUID            "2D7A9F0C-E0E8-4CC9-A71B-A21DB2D034A1"
#define BEACON_UUID_REV        "A134D0B2-1DA2-1BA7-C94C-E8E00C9F7A2D"
#define CHARACTERISTIC_UUID    "82258BAA-DF72-47E8-99BC-B73D7ECD08A5"

BLEServer *pServer;
BLECharacteristic *pCharacteristic;
bool deviceConnected = false;
uint8_t value = 0;

class MyServerCallbacks: public BLEServerCallbacks {
    void onConnect(BLEServer* pServer) {
      deviceConnected = true;
      Serial.println("deviceConnected = true");
    };

    void onDisconnect(BLEServer* pServer) {
      deviceConnected = false;
      Serial.println("deviceConnected = false");

      // Restart advertising to be visible and connectable again
      BLEAdvertising* pAdvertising;
      pAdvertising = pServer->getAdvertising();
      pAdvertising->start();
      Serial.println("iBeacon advertising restarted");
    }
};

class MyCallbacks: public BLECharacteristicCallbacks {
    void onWrite(BLECharacteristic *pCharacteristic) {
      std::string rxValue = pCharacteristic->getValue();

      if (rxValue.length() > 0) {
        Serial.println("*********");
        Serial.print("Received Value: ");
        for (int i = 0; i < rxValue.length(); i++) {
          Serial.print(rxValue[i]);
        }
        Serial.println();
        Serial.println("*********");

      }
    }
};


void init_service() {
  BLEAdvertising* pAdvertising;
  pAdvertising = pServer->getAdvertising();
  pAdvertising->stop();

  // Create the BLE Service
  BLEService *pService = pServer->createService(BLEUUID(SERVICE_UUID));

  // Create a BLE Characteristic
  pCharacteristic = pService->createCharacteristic(
                      CHARACTERISTIC_UUID,
                      BLECharacteristic::PROPERTY_READ   |
                      BLECharacteristic::PROPERTY_WRITE  |
                      BLECharacteristic::PROPERTY_NOTIFY
                    );
  pCharacteristic->setCallbacks(new MyCallbacks());
  pCharacteristic->addDescriptor(new BLE2902());

  pAdvertising->addServiceUUID(BLEUUID(SERVICE_UUID));

  // Start the service
  pService->start();

  pAdvertising->start();
}

void init_beacon() {
  BLEAdvertising* pAdvertising;
  pAdvertising = pServer->getAdvertising();
  pAdvertising->stop();
  // iBeacon
  BLEBeacon myBeacon;
  myBeacon.setManufacturerId(0x4c00);
  myBeacon.setMajor(5);
  myBeacon.setMinor(88);
  myBeacon.setSignalPower(0xc5);
  myBeacon.setProximityUUID(BLEUUID(BEACON_UUID_REV));

  BLEAdvertisementData advertisementData;
  advertisementData.setFlags(0x1A);
  advertisementData.setManufacturerData(myBeacon.getData());
  pAdvertising->setAdvertisementData(advertisementData);

  pAdvertising->start();
}

void setup() {
  Serial.begin(115200);
  Serial.println();
  Serial.println("Initializing...");
  Serial.flush();

  BLEDevice::init(DEVICE_NAME);
  pServer = BLEDevice::createServer();
  pServer->setCallbacks(new MyServerCallbacks());

  init_service();
  init_beacon();

  Serial.println("iBeacon + service defined and advertising!");
}

void loop() {
  if (deviceConnected) {
    Serial.printf("*** NOTIFY: %d ***\n", value);
    pCharacteristic->setValue(&value, 1);
    pCharacteristic->notify();
    value++;
  }
  delay(2000);
}

The screen shot showing the esp32 above as a bluetooth device and missing the iBeacon properties:

I found the solution. Apparently the proximity uuid is emitted in reversed order. The solution is to set your uuid as follows:

BLEUUID bleUUID = BLEUUID(SERVICE_UUID) ;
bleUUID = bleUUID.to128();
myBeacon.setProximityUUID(BLEUUID( bleUUID.getNative()->uuid.uuid128, 16, true ));

Credits to this GitHub issue: https://github.com/nkolban/esp32-snippets/issues/385