I am running EL Capitan, and I have a MOTU Ultralite which is my main midi interface, but I also have a MOTU 828 mk2 and a Kenton midi box which splits the midi in into 5 midi outs, if that is of any help.
I was using build 5.3.85, I have now installed the latest build. I have followed the steps listed here, and can now check the options that I previously could not, but I still cannot get the panel to control my MKS50.
I am running the MKS50 on midi channel 3 and the audio is coming back in through audio inputs 7-8. I can provide screen grabs of every stage of the process I am following, if that helps?