thanks a lot for your fast answers!

yes I’ve used the midi seq a lot of time, i known how it’s work.
I’ve no idea what is the source of my problem.

I’ve tried to (in all combinations as possible) :

  • test all mini chanels / nothing happened
  • many cables / nothing happened
  • look around the options menu (midi, sync,) /nothing happened
  • with an ext clock / OT is synchronized but the clock is not transmitted
  • with an int clock / nothing happened
  • powered with midi Out and Thru a midi solution merger / it’s worked !
  • send some midi CC, portamento / nothing happened
  • downgrade OS /nothing happened
  • upgrade OS / nothing happened
  • test mode / who tells me : there are no problem on my octatrack
  • test with many diferent sort of midi hardware like doepfer darklink, motu 828, waldorf stuff, etc. / nothing happened

I am desperate because I don’t know how to solve this problem