peripheral:didModifyServices() not called in the background?

I have CoreBluetooth set up on my app as a Central with the CBCentralManagerDelegate implemented to scan for peripherals with my service. I also have the

bluetooth-central

Info.plist

Once connected, I discover services and read any characteristics I need. When a service is modified or added on the Peripheral side, I respond to the peripheral:didModifyServices: method, and rediscover services, which is working fine in the foreground.

My issue is that when my app is in the background, and the Peripheral I'm connected to adds a service, the peripheral:didModifyServices: method is not called. But ONLY that method is not called when my Central app is in the background. The other CBPeripheralDelegate methods (peripheral:didDiscoverServices:, peripheral:didDiscoverCharacteristicsForService:error:, etc) are all received when my app is in the background.

Is this behavior correct for the

bluetooth-central

CBCentralManagerDelegate:

func centralManagerDidUpdateState(_ central: CBCentralManager) {
  if central.state == .poweredOn {
  central.scanForPeripherals(withServices: [primaryService], options: nil)
  }
}

func centralManager(_ central: CBCentralManager, didDiscover peripheral: CBPeripheral, advertisementData: [String : Any], rssi RSSI: NSNumber) {
  if let name = advertisementData[CBAdvertisementDataLocalNameKey] as? String {
  print("Discovered peripheral " + name)
  peripheral.delegate = self
  connectedPeripherals.insert(peripheral)
  central.connect(peripheral, options: nil)
  }
}

func centralManager(_ central: CBCentralManager, didDisconnectPeripheral peripheral: CBPeripheral, error: Error?) {
  connectedPeripherals.remove(peripheral)
}

func centralManager(_ central: CBCentralManager, didFailToConnect peripheral: CBPeripheral, error: Error?) {
  connectedPeripherals.remove(peripheral)
}

func centralManager(_ central: CBCentralManager, didConnect peripheral: CBPeripheral) {
  peripheral.discoverServices(nil)
}

CBPeripheralDelegate:

func peripheral(_ peripheral: CBPeripheral, didDiscoverServices error: Error?) {
  for service in peripheral.services ?? [] {
  if isRecognizedService(service) {
  peripheral.discoverCharacteristics(nil, for: service)
  }
  }
}

// This is not called in the background!
func peripheral(_ peripheral: CBPeripheral, didModifyServices invalidatedServices: [CBService]) {
  print("Peripheral services changed...")
  peripheral.discoverServices(nil)
}

func peripheral(_ peripheral: CBPeripheral, didDiscoverCharacteristicsFor service: CBService, error: Error?) {
  guard error == nil else {
  print("Error discovering characteristics...")
  return
  }

  guard let characteristics = service.characteristics, !characteristics.isEmpty else {
  print("No characteristics found for service...")
  return
  }

  for characteristic in service.characteristics ?? [] {
  // Subscribe to characteristic changes, etc...
  }
}