Open the Apple Menu > About this Mac > More Info > System Report >USB and check that the Controller appears here in the USB Device Tree.Make sure the Controller is connected directly to the USB port on the Mac.If your USB MIDI Controller is not working on a Mac please check the following: This has now been found on a number of different MIDI Devices including Impulse, SL MkII, Launchpad S, Launchkey, etc.
This causes odd behaviour, such as Devices not being available for use in programs, missing ports, Automap Buttons not working or connecting. We have seen a small number of users with various Class Compliant USB MIDI Devices have an issue using Mac OS where the MIDI Devices do not appear properly to the computer.
