C/C++ Question Pin interrup issue in LoRa library only in B4R project

ISR_PREFIX void LoRaClass::onDio0Rise()
{
   LoRa.handleDio0Rise();
}
void LoRaClass::handleDio0Rise()
{
   int irqFlags = readRegister(REG_IRQ_FLAGS);
   Serial.print("irqFlags=");Serial.println(irqFlags); //debug******************
//=> irqFlags should be "80" but with B4R it is "00"
  // clear IRQ's
  writeRegister(REG_IRQ_FLAGS, irqFlags);

  if ((irqFlags & IRQ_PAYLOAD_CRC_ERROR_MASK) == 0) {
    if ((irqFlags & IRQ_RX_DONE_MASK) != 0) {
//=> du to irqflags=00, never we come in this part, never we received a packet
       Serial.println("receive packet");//debug*********************************
      _packetIndex = 0;

      // read packet length
      int packetLength = _implicitHeaderMode ? readRegister(REG_PAYLOAD_LENGTH) : readRegister(REG_RX_NB_BYTES);

      // set FIFO address to current RX address
      writeRegister(REG_FIFO_ADDR_PTR, readRegister(REG_FIFO_RX_CURRENT_ADDR));

      if (_onReceive) {
        _onReceive(packetLength);
      }
    }
    else if ((irqFlags & IRQ_TX_DONE_MASK) != 0) {
      if (_onTxDone) {
        _onTxDone();
      }
    }
  }
}

//added for B4R
void LoRaClass::processing()  {
   if (digitalRead(_dio0)== HIGH) {handleDio0Rise(); }  //test of pin dio0 used for interruption
   }  
ISR_PREFIX void LoRaClass::onDio0Rise()
{
  //LoRa.handleDio0Rise();
}
void LoRaClass::handleDio0Rise()
{
  int irqFlags = readRegister(REG_IRQ_FLAGS);

  // clear IRQ's
  writeRegister(REG_IRQ_FLAGS, irqFlags);

  if ((irqFlags & IRQ_PAYLOAD_CRC_ERROR_MASK) == 0) {

    if ((irqFlags & IRQ_RX_DONE_MASK) != 0) {
      // received a packet
      _packetIndex = 0;

      // read packet length
      int packetLength = _implicitHeaderMode ? readRegister(REG_PAYLOAD_LENGTH) : readRegister(REG_RX_NB_BYTES);

      // set FIFO address to current RX address
      writeRegister(REG_FIFO_ADDR_PTR, readRegister(REG_FIFO_RX_CURRENT_ADDR));

      if (_onReceive) {
        _onReceive(packetLength);
      }
    }
    else if ((irqFlags & IRQ_TX_DONE_MASK) != 0) {
      if (_onTxDone) {
        _onTxDone();
      }
    }
  }
}