MIDI Keyboard with Sonic Pi No Audio

use_real_time

in_thread do
  while(1) do
      note, vel = sync "/midi:midi_through_port-0:0:8/note_on"
      play note, amp: vel/127.0
    end
  end

works for me on v3.2.2, Linux 5.4.0-47-generic #51~18.04.1-Ubuntu x86_64 but obviously there are several colons : in the sync path. Am I missing something?