Pass() >> Port(n) // Print('xyz') outputs to port 1 as well (jack)

[LeMikaelF]

When using 'jack' or 'jack-rt' backend, when the command Print() is in parallel with another command, such as Pass() or Transpose(), and that the command sends to a port number higher than 1, it also causes port 1 to activate.

Consider:

config(
  backend='jack',
  in_ports = 1,
  out_ports = 2,
)
run(
  Pass() >> Port(2) //
  Print('test')
)

This will output MIDI signals to port 1 and 2. The workaround I am using is to simply use a dummy port 1 and leave it unused.