HI again Ed,
What I do is set the Midi controller to default and try to MIDI learn from the KeyLab but it never picks up the knob movements.
This works for me with my Novation Controller in my DAW Studio One 3 using VST3 64 bit version 3.0.2.1289. Are you moving the controllers all the range?
It also works when AL3 is in standalone mode here. Shall i understand your MIDI learn work with AL3 in stand alone mode?
Perhaps this is about how your controller and MCC is setup. Are you sure it's set up correct?
The problem is with the VSTi I think and not with KeyLab since I can override the knobs and faders and use it with KeyLab.
Does this mean, that MIDI learn does work, when you do something else? What settings are you using here?
Have you tried the things i suggested to look at in the other thread?
Have you search the different Arturia controller and MCC forums , if there is any help there?