"Array of MIDI-Interfaces" - how?

Projects Interfacing w/ Software on the Computer
2

I just tried the following. It compiles with no errors but it does not work - the read()-method does never show any events...

#include <MIDI.h>

MIDI_CREATE_INSTANCE(HardwareSerial, Serial1, midiA);
MIDI_CREATE_INSTANCE(HardwareSerial, Serial2, midiB);
MIDI_CREATE_INSTANCE(HardwareSerial, Serial3, midiC); 
midi::MidiInterface<HardwareSerial> m[3]={
  midiA,midiB,midiC};

void setup()
{
  Serial.begin(115200);
  Serial.println("Start");
  
  m[0].begin(MIDI_CHANNEL_OMNI);
  m[1].begin(MIDI_CHANNEL_OMNI);
  m[2].begin(MIDI_CHANNEL_OMNI);
}

void loop()
{
  byte in_port;
  
  for(in_port=0;in_port<3;in_port++)
  {    
    if(m[in_port].read())
    {
      Serial.print("incoming port: ");
      Serial.print(in_port,DEC);
      Serial.print(" data1: ");
      Serial.println(m[in_port].getData1());
    }
  }
}