MX-5/MX-6/MX-9 and Fractal Audio Axe-Fx I/II(XL+)/III/FM3/FM9

Because the MX-5/MX-6/MX-9 has no LCD, there is no need to sync data.
This means you only need ONE midi cable from MX Midi Out -> Fractal Midi In
Don't use specific "AFX1/2" and "AFX/FM3" commands.
Instead use "Preset (PC)" and "Scene/Snapshot"
use "CC On Only" CC# 14 for Tempo
use "CC On/Off " CC# 15 for Tuner

You need to adjust following setting on the Fractal:

SETUP - MIDI/REMOTE

Tab General
  Midi Channel: 1
  Display Offset: 0
  Midi PC Offset: 0

Tab External
  External Control 1: 16 (Standard/Ultra/Axe-Fx II(XL+)
                       1  (Axe-Fx III/FM3/FM9) 
  
Tab Other
  Tempo Tap: 14
  Tuner: 15
  Preset Increment: none
  Preset Decrement: none
  Scene Select: 34