This is a reply to Arturia support concerning problems I experienced with the Arturia Keyab 61 mk2 and Cubase 10.5. My problem was inadvertantly creating duplicate Mackie Controls! It might help you.
I couldn’t understand why the transport controls weren’t working well because I have upgraded from a Keylab 49 mk2 to a 61 mk2 and everything was ok before. Having spent a while running through all the possibilities i decided to check the “Studio Set Up” in Cubase 10.5 . I had Mackie control duplicated and initially after changing the “Midi in2” etc to “Not Connected” on the duplicate Mackie Control (2)l things worked better but still the channel selection didn’t work properly. i then wondered if even though the “Keylab Midi In and Out 2” were disconnected that somehow the “User Commands” might be a problem and well… yes they were. I removed them and everything worked. I then realised that I could just get rid of “Mackie Control 2” altogether which I did. Moral of the story is don’t end up with duplicate Mackie controls !!!