Wow, been wasting hours and hours of trouble shooting why my Keylab MKII 61 & 88 controllers doesn't work in Reaper, using buttons/sliders.
Some say you should enable both "Keylab MK II xx" and "MIDIIN2 (Keylab MK II xx)" and others say you should NOT use "MIDIIN2 (Keylab MK II xx)" etc. and control enabling has the same confusion.
Same applies for settings under "Control/OSC/web" with different recommendations and even homemade solutions.
Arturias Keylab MKII support page has outdated recommendations (some even removed).
To my understanding, the complexity might be related to different hardware and OS's (?).
Anyway, here's my contribution for a guideline and please note this applies for the following system configurations:
OS: Win 11 (64) May update
DAW: Reaper
Midi controllers: Keylab MKII 61 & 88
Soundcards: Zoom F6/Nvidia RTX 3060/Realtek
Here we go:
In Reaper, go into "MIDI Device" (Reaper Preferences, Ctrl-P)
Enable BOTH "Keylab MK II xx" (Enabled+Control) AND "MIDIIN2 (Keylab MK II xx)" (Enabled+Control), under Midi inputs.
Enable BOTH "Keylab MK II xx" (Enabled) AND "MIDIOUT2 (Keylab MK II xx)" (Enabled) under Midi Outputs
Select "Control/OSC/web" and add "Mackie Control Universal", select "MIDIIN2 (Keylab MK II xx)" for MIDI input and "MIDIOUT2 (Keylab MK II xx)" for MIDI output and secure all tick boxes are de-selected.
In my rig(s), everything works smoothly, as of 12th of June 2022
