HI all , ill try and help if i can as i know a bit about macs . first i need to know if beatstep is working at all on your mac .best way to do this is plug in beatstep and go to your apple sign in the top left hand corner and press about mac ,then more info, then system report, then hardware/usb.
can you see beatstep in the usb hub? if so this is good there a correct connection. if not try a different usb2 lead not a usb one.
i'm guessing you have tried unplugging all other devices and only using the beatstep .
let me know if this helps and we can take it from there.
ps this is osx only guys