looks more like a hardware issue, than ‘settings’
I think midi monitor allows you to see the bytes of the invalid messages , that would be interesting.
but the fact you’re also getting identical timestamps is very suspicious of a corrupt stream.
what I would do is simplify…
remove everything else thats not needed for test,
make sure no midi input to octatrack (midi loops)
turn clock off, also for now,
turn off midi output of the audio channels. (also check they are not on same ch. as your using for midi output)
all, so you know exactly what is being sent over the wire.
also make sure that the octatrack is NOT using turbo midi … it shouldn’t unless it negotiated it with something but who knows
then down to normal stuff, perhaps try a different midi cable, midi -> usb converter.
this is part of the MIDI protocol , all midi implementations are required to support this,
anyway, usb converters are usually dumb, they dont interpret messages they just repack them.
(as opposed to midi processors which have to unpack to be able to change them)
we are also not seeing this in the midi monitor above, as note with velocity =0.
(midi monitor has an option to choose if you display as note_on,vel=0 or to display as note off)
Id assume its those ‘invalid’ 2 byte messages are the note offs.
im intrigued by what those 1 byte ones are…perhaps corrupted clock messages.