I found a clunky workaround I only tested on MacOS Sierra for now.

I'm automatically setting the MIDI in every 200 ms, using a metro that sends [midi-dialog 2 0 0 0 0 0 0 0 0 2 1 0 0 0 0 0 0 0 4 4(    to    [s pd]

It seems to work, but of course I suspect messages are getting lost.

Cheers,

Mario