MIDI.sendRealTime seems not working properly over USB

[LinkeHand]

I installed the example code "AllEvents" on my Arduino Leonardo.

Most time, I do not get the Midi-NoteOn-Message from this example on my USB-Port. I Checked it with midi-ox unter windows 10 and even unter Ubuntu.
It seems that sending a MIDI-SendRealTime message like "MIDI.sendRealTime(MidiType::Clock);" corrupts a following Midi-Message most times.
I disabled the output on serial port an still got this error.
I changed the MIDI-sendRealTime - Message from "Clock" to "Start". I get still this error.
I added a second MIDI-sendRealTime-Message in the example code. I only see the first MIDI.sendRealTime-Message in midi-ox.

I don't have a clue.

Regards Bernd

[LinkeHand]

Supplement: I reduced the example code AllEvents to this:

#include <USB-MIDI.h>

USBMIDI_CREATE_DEFAULT_INSTANCE();

unsigned long t0 = millis();
unsigned long tClock = millis();

using namespace MIDI_NAMESPACE;

// -----------------------------------------------------------------------------
//
// -----------------------------------------------------------------------------
void setup()
{

}

// -----------------------------------------------------------------------------
//
// -----------------------------------------------------------------------------
void loop()
{

// send a note every second
// (dont cáll delay(1000) as it will stall the pipeline)
if ((millis() - t0) > 1000)
{
t0 = millis();

byte note = random(1, 127);
byte velocity = 55;
byte channel = 1;

MIDI.sendNoteOn(note, velocity, channel);
MIDI.sendNoteOff(note, velocity, channel);

}

if ((millis() - tClock) > 100)
{
tClock = millis();
MIDI.sendRealTime(MidiType::Clock);
}
}

And here a a few lines out of my log in midi-ox:

00007BE4 5 -- F8 -- -- -- --- Timing Clock
00007C16 5 -- F8 -- -- -- --- Timing Clock
00007C36 5 -- F8 -- -- -- --- Timing Clock
00007C5A 5 -- F8 -- -- -- --- Timing Clock
00007C62 5 -- 80 0F 37 1 Eb 0 Note Off
00007C76 5 -- F8 -- -- -- --- Timing Clock
00007CA7 5 -- F8 -- -- -- --- Timing Clock
00007CD4 5 -- F8 -- -- -- --- Timing Clock
00007CF9 5 -- F8 -- -- -- --- Timing Clock
00007D2A 5 -- F8 -- -- -- --- Timing Clock

The complete log is here

Arduino-midi.log

regards Bernd